While reading manymanymany fan fictions and original stories with varying levels, it popped into my mind a few tricks to decrease the Mary Sue aspects from characters. I've sorted the tricks to different categories, hope they are useful! The categories are,
- What is a Mary Sue anyway? And why people create them?
- Before creating him/her, aka General attitude
- When creating him/her
- When writing about him/her
- Notes about fan characters
- Notes about original characters
- Links to other Anti Mary Sue tutorials
Most the tricks I've mentioned in this guide are good to remember all the time. However, the tricks I've marked with a star symbol (*) are optional, kind of extra tricks. I use quite harsh examples in the guide to make stuff clear, but remember that the flaws that are smaller than the ones that I mentioned can be bad, too!
On the other hand: Generally, NONE of mentioned flaws are ABSOLUTELY bad, so you don't necessarily have to throw your character into recycling bin or start to remake him/her if you see that one kind of flaw in him/her. You just have to pay more attention to him/her and be warned about not to portray him/her in too Sue-ish way. Characters having SOME Mary Sue characteristics are not doomed, but they are in danger. Little Sue-ish characters are good as long as the author doesn't go too wild.
And: Since I don't speak English as my mother tongue, the tutorial may contain the grammar errors. If you note an error, feel free to tell me about that. I learn via my flaws! Characters mentioned in the end the tutorial belong to their respectful owners, of course.
In this tutorial, with FC I mean fan character, meaning character that is made for a certain fandom (like, a character that adventures in the world of Naruto or Harry Potter). With OC, I mean original character, meaning character that you create for a story world that is invented by you (your own fantasy world etc.). With just character, I mean both FCs and OCs. (Why I explain this is the fact that particularly out of dA, OC is often used instead of FC when meaning fan characters, so to avoid confusion.)
Also check out my tutorial about character flaws, they are closely related to Mary Sues!
And now to the tutorial.
QUICK (?) TRICKS TO DECREASE YOUR CHARACTER'S MARY-SUENESS
W H A T I S A M A R Y S U E A N Y W A Y ?
A N D W H Y P E O P L E C R E A T E T H E M ?
Whether you are reading this tutorial just for curiosity, or you are advised to read this tutorial, or you are generally looking for information about Mary Sues and how to prevent making them, I keep here explanation about what is a Mary Sue anyway (or, to be accurate, what is it in my vision) and phenomena relating to them.
So. Mary Sues are usually defined to be "overall perfect characters with far too minor flaws, having illogical powers and traits, lacking personality and usually being fulfillments the fantasies of the author". This is quite correct but also rather blunt definition. Many, many Mary Sue creators (also known as Suethors) have heard of this definition and even say they hate Sues, but still they do Sues. So, they can't recognize that there is something wrong with their characters, and they can get even fiery when someone notes about the issue. Why?
The problem can consist of the following issues:
1) They don't have exact image about what is exactly a Sue, or the image is very black'n'white. I have met some people that claimed that their characters aren't Sues, because the characters are not OVERALL PERFECT - they had this and that minor flaws that appeared in the character's info sheet but not in the stories. Not talking about those TURBOBOOSTÜBERPOWAAAHS the characters had and which weren't balanced with reasonable weaknesses. The creators believed that minor cracks is enough to make their characters non-Sues, which wasn't, sadly, true. I hope this tutorial can declare you better what is a Sue than how they understood.
2) The creator grows too attached to his/her character that (s)he can't see the character is slipping to the Sueness. The best cure to that is to show the character to ADULT and EXPERIENCED writer and ask what he/she honestly thinks about the character. Prefer to ask not-so close people instead of your closest friends and such: friends are often afraid to upset you if they note something grave bad in your character, and they can also empathize you so much that they can be biased.
It's best to offer the critic a written piece about your character's story in addition to the character sheet, or at least portrayal about what is the world where the character lives. At least I have difficulties with evaluating if a character is a Sue or not if I see only the character sheet without a context.
Also, attachment problem can be partially prevented by making the character distant enough from the author. More in the tutorial.
3) The creator is trying to create "something cool" and fails in understanding so-called "Rules of Coolness" (as lacking the better name). This is easier to understand with some experience, but to put short: usually, young/inexperienced character creators (but, usually the very young ones) tend to think that the more super powers the character has, the prettier (s)he is and the more awesome personality (s)he has, the better character is. Like a small child decorating a cake with heaps of sprinkles and buttercream, that much that they are running over the cake.
However, this may not always work.
Think again: Do you REALLY want to create a character that has no excitement in his/her life? Why should (s)he has awsum powers for every single problem while you can make more excitement by making him to worry, "Damn! There is a problem, how to solve it before cannibals come to eat me?" Or the personality? If we can ALWAYS assume that your character is always right and never makes mistakes... well, there is no room for the character development, and THAT'S utterly boring.
Ask yourself what you want to read when reading a story belonging to the genre of which you are writing. You probably start to think about issues like excitement, humor, sappy romance etc. Well, let's stick on the excitement. What causes excitement? Being not able to predict exactly what happens next. Surprises. Taste of danger and lingering "oh s**t how can I survive" feeling. Jumping into the hero(ine)'s shoes and feeling the adrenaline in his/her veins. THAT'S IT. Don't make stuff too easy for the hero(ine), otherwise the readers lose the excitement!
After that blabbering, to the guide itself!
B E F O R E C R E A T I N G H I M / H E R ,
A K A G E N E R A L A T T I T U D E
Remember that your character is a tool of the story; (s)he is NOT you, NOT your friend, NOR your child.
Too much affection to your character makes his/her objective using really difficult. If you can't detach the character from yourself enough, you easily want to protect the character and pamper him/her with special skills. Luckily that thing usually eases as you gain more experience, but in start, it helps a lot if you can use methods that put a clear limit between you and your character.
An easy trick to make you can see more objective your character is to make him/her clearly different from you, both in good and bad. It doesn't automatically make him/her non-Sue, but it may prevent you from "protecting" him/her too much because of your affection and feeling of similarity. Unless you are making well-thought self-insert, never name your character after you, because it makes it really difficult to not to think character as a tool and not as your avatar. (I've experienced that.) Thus, it makes more difficult to set him/her to situations that you don't want end up to, and makes more tempting to put him/her situations you want to experience (like, being popular among people).
Hint! You can still give the characters some traits of you, like your shyness, your optimism or you interest in shiny things. In fact, giving the author's traits to characters makes the writing process easier, since author knows well how these traits work. But still be careful to not to make him/her too much like you!
Make the character to serve your story, not your story to serve your character.
This is something many suethors forget. You should use the character to make the plot more interesting, not the plot to make the character feel comfortable. For example, if you give your character a new cool skill, you should give it to use it later as plot device, not because you want to pamper your darling with new toys.
How can the character serve the story, then? By keeping the reader's attention - or, mostly, by being entertaining in some way! Entertaining doesn't mean same thing than funny in this context: it means that the character manages to entertain the reader in some way, or invoke emotions. Character can be, for example, the reader's vessel through crazy adventures, a traveling buddy through the story (and the person who asks things that the readers would like to ask), a co-thinker in troublesome moral questions, or - of course! - a funny creature to which the reader can laugh. Think about characters that you like and try to think why do you enjoy reading about them - and how they serve the story.
In certain way, story can serve the character, of course: you can arrange situations that highlight the most entertaining sides of the character!
Avoid using your character just as fulfillment of your fantasies.
It may be fun to write your own daydreams down, but it is not as fun to read other people's fantasies. In fact, it is really boring. Twilight is a great example about that. Writing day dreams is fine, but before you publish it, think about if it is entertaining in the reader's opinion.
Your characters can't make YOU anything bad, even if you put them evil situations.
Don't be afraid to cause problems for the characters or make not their wishes to become true! They can't bite you even if they want to, because they are just beings of your imagination. So, you can feel safe to torture them as much as you like > Be merciless enough!
Saying you hate Mary Sues doesn't automatically make your characters non-Sues.
Some people mistakenly think that if they once learn what a Mary Sue is, automatically they won't make them anymore. This is not exactly true: first, even if you know the term "Mary Sue", it's not sure if you know ALL aspects about the issue or the heart of the Sueism. For example, I met a girl that claimed that her character is not a Mary Sue, because the character had minor weaknesses. She thought that Mary Sue is a character that is overall perfect and that a Mary Sue turns into a non-Sue if you slap on them couple of small weaknesses. Unfortunately, that's not true; if the character is perfect aka badly Sueish, you have to do him/her a harsh renovation. Minor one is not enough. Also, the weaknesses need to be certain kind of weaknesses to make a difference, as spoken in my character flaw review.
In reality, Mary Sues are usually more sneaky creatures than easily recognizable perfect!Sues. They may surprise even their creators; you just be told that that "Your character happens to be a Sue, she doesn't seem realistic since all the good happens to her". Before you can really say if your character is a Sue or not, you have to get WELL known about the term.
Second thing about "I-don't-make-Sues-cos-I-hate-them" issue: even people that have written man years and fully understand what is a Sue are in danger of making Sues. They may get too excited about creating a cool character or character that resemble they too much, and thus get affected to the character that much that they can't see that they are creating Sues. The danger lurks everywhere. However, usually good writers are capable to sense if their characters are in danger to slip to the Dark Side, so they can ask other opinions from other good writers.
Generally: when in doubt, ask more experienced writers.
W H E N C R E A T I N G H I M / H E R
Personality. Create it. Properly. IT IS THE CORE OF THE WHOLE CHARACTER.
When people describe generic Mary Sues, one of first things they mention is that the character lacks personality, or the personality is very flat and full of clichés. While that, most of most loved characters ever have are loved because of their interesting personality and/or past. Without personality, the character is just a paper doll with fancy clothes, so pay HUGELY attention to their behavior patterns and traits.
Here is some kind of check-list for the personality of a character. Please note that this list CAN'T totally prevent from getting the character Sueish, but at least it can prevent the silliest mistakes. So, to it:
- Check out that the personality of the character is logical, and it causes logical consequences. For example, if your character is the only hippie orc in a blood-lusty orc village, he must have serious difficulties in his life there, like getting discriminated and such. Also, if there is insanely big heaps of difficulties in your character's life, it's unlikely (s)he is perfectly happyhappyjoy person or even perfectly sane. Gimme some logic, and inspect real people.
- Think the characters' personality through, reflecting it to his/her history. In other words, as thinking about the character's personality, try to step into the character's shoes and see how (s)he really works. For example, think about plot twists from point of view of the character, and as trying to forget your own mannerisms, try to think how your character would react to the situations. It may be difficult if the characters is very different from you, but it is worth it. Creating simple thumb rules about the character's personality (like, "he rarely thinks before speaking") and inspecting and interviewing people help a lot.
- Avoid giving character traits just because they are cool. Okay, couple of them are right, but if the character is just a collection of traits you regards as cool, it's unlikely to make him/her achieve the depth. Make the character wholeness, not a collection. Wholeness is something that forms a clear entirety, and everything is naturally linked together. Collection is a bundle of random pieces.
- Also: Avoid making the (leading) character ONLY to fulfill a certain character type (like 'typical shounen hero', 'typical action girl', 'emo', 'kawaii desu cuteness case', 'tsundere' etc.). At least in my opinion, a well-done leading character is something that you can think as '(s)he is [character's name]' and not as '(s)he is tsundere/uke/emo/etc.'. Of course character types can be used when creating supporting characters ('We need a beardy guy to babble wise things'), and they can be also used as a base of leading character ('What about making a nerd as a hero?'). However, your character WON'T stay in anyone's mind if (s)he is just example of some type and has nothing unique in him/her.
- DO NOT COPY LINE-BY-LINE AN UNIQUE PERSONALITY FROM ANOTHER CHARACTER (UNLESS IT IS YOURS)!!! If the reader knows that another character, you are in a big trouble. However, you can still get inspiration from other characters and base your ones to them, but at least DO NOT copy the unique quirks. For example, any Naruto fan can see that you are copying Rock Lee & Might Guy if you create a guy/girl yelling about power&youth and wearing green jumpsuit.
- Don't just randomly list traits, make them shore each others. And most importantly, DO NOT put into the same character two traits that CANNOT exist in the same personality. For example, it's wrong to say that the same person is simultaneously quiet and talkative - she can be SOMETIMES quiet and SOMETIMES talkative, in other words his/her talkativeness depends on the situation. If you give perfectly opposite traits to the same character, people may think that you didn't think about his/her personality well but just chose random adjectives, even if you didn't. So, be really careful when choosing the words.
Instead, it's pretty good idea to put into the same character two or more traits that are not usual together (but are possible together). For example, we all have seen in TV a spoiled brat that always gets her daddy what she wants and that despises "lower" people. Then, Disney make difference and made one of their character badly spoiled naive brat that wants to marry a prince and gets always what she wants, but WITH lots of empathy and a golden heart. The result, Lottie from The Princess and the Frog, was priceless.
- Write his/her personality down as a TEXT, not as a LIST. Text is far better tool to handle the relations of the traits than lists: if you character is told to be "really shy, and she usually bursts her stress out by talking fast about a lot of random issues popping into her mind that second", it tells far more than just listing "she is shy and talkative", because it tells how they are connected and how they even can exist in the same character. Plus, Sue-haters usually see "list personality" more Sueish than "text personality".
- And, finally: Your character's personality doesn't have to be ready when you start to write about him/her. This applies particularly with characters in long stories and RPGs. Usually writing about them shapes them more, so don't stress about making the personality detailed enough! Let your baby grow up
Don't make him/her simultaneously very well-liked AND very good-looking AND very skilled AND very wise.
If used all four in one, it's nearly automatically a Sue. Instead, decrease them AT LEAST in one area, or half in two areas, or third in three areas, and so on. However, I recommend decreasing MORE than the amount of one area.
Example: Naruto is quite nice but annoying in some people's opinion (½ points), not too good-looking but not bad-looking either (½ points), VERY skilled in ninja arts (1 point) and mostly dumb but sometimes quite quick-minded in battle (1/3 points). Together, 2 + 1/3 points instead of full 4 points. I removed stuff for 1 + 2/3 points.
All people can't be either his/her friends or his/her enemies - especially not just either of them.
It's is quite dumb to read about person that is liked by all or hated by all. Neither of these situations is realistic; there are people that don't like person that is liked by most people, and even hated people usually have someone that cared of them. It is also rather silly to justify that "those people who don't like her are MEAN!!!" People get along with different people: for example, some of them can't do well with silent people, while some can't stand motormouths. It's a personality issue.
And, in reality, a person has usually just a bunch of people that (s)he can call either friends or enemies. Most people that he interacts with doesn't think anything special about him. For example, I can bet that most of the buddies in your school don't pay attention if you are in the school or not, even if they know your face. So, be sure that if you character lives in a place with lots of people, she can occasionally meet people that doesn't think anything special of your character. Also, make him/her being both liked and hated.
Take easy with the looks.
The outlook isn't crucial in Sueness: a good character can look super sexy, and a Mary Sue can look normal. However, the looks is a thing that the reader sees first, and by it (s)he often makes his/her first impressions about the character's Sueness. Some basic rules:
1. Stick to the genre / series that you are writing about. Here is no neon-pink-haired girls in LotR or neko-eared guys in Naruto or blondes or redheads in Avatar: The Last Airbender. People living in the Feudal Japan use neither sneakers nor jeans. The better the looks suits to the series, the... yeah, better. Research is your friend, both with FCs and OCs.
2. Avoid cliché attires if possible. There is enough of emo clothing, sailor school uniforms, cat ears, kitsune tails, scars running over one's eye, and angel wings. Be creative and try something new instead!
3. Give him/her just few special attires for his/her outlook. For example, odd-colored eyes or hair are totally enough in most cases, no need to add decoration wings or stuff!
4. Choose for his/her costume max four main colors and their variations and stick to them. For example, in Naruto Part I the main character Naruto uses mainly orange, dark blue and some white in his costume. You can use other colors in minor details, like Naruto uses red in the back of his jacket, grey in the jacket's zipper and green in his necklace given by Tsunade. The result seems more controlled than fuzzy cocktail of all colors of rainbow!
5. If making FCs, do not make your character's costume notably more complicated/pretty than the leading cast has, unless your character is meant to portray something with high authority (like the king of a kingdom). But is (s)he is the same level (like fellow ninja), stick on the same complicatedness/coolness level.
6. If your character seems amazingly beautiful and sexy, (s)he should be also really bad in something else. Beauty is a notable strength: beautiful people have usually better self-confidence and tendency to socialize then not-so-pretty people, because they trust that their looks don't push people out.
7. DO NOT DIRECTLY COPY A UNIQUE THING FROM A WELL-KNOWN CHARACTER, ESPECIALLY IF THAT CHARACTER APPEARS IN THE SAME SERIES. Taking influence, altering, fine. Direct copying to the character without any thinking, NOT FINE.
Thumb rule: Good looks can't save poor made character, and bad looks doesn't hide the amazingness of well made character. See also the section Choosing right words for his/her description can decrease Sue aspects greatly in section When writing about him/her.
My tutorial about character design: Clickie.
Also, take easy with his/her background.
Good characters don't need to have background about which you can make a Hollywood movie (though they still CAN have). Of course (s)he can always have not-too-big tragedies, like being school-bullied in his/her past, but being the only survivor of his/her lineage is not something you should use very often. What the readers want to read is what they are NOW, not their angst-filled pasts. Of course, the past can (and should!) shape them, but don't use it just for gathering sympathy for your character: the personality of him matters.
For example, I generally dislike boyfriend characters in shoujo series, because they are usually meant to (be eye food and) cause pity to their ohsotragic past. However, a shoujo series called Chibi Vampire makes a nice exception: its boyfriend character, Kenta, doesn't have bishie looks, but he has personality; at least I'd like to know a person like him, because his personality is so real. Yup, still talking about past: Even if his past without father and in great poverty is indeed tragic and causes a lot of unhappiness (that is one of plot tools in the series), his personality is put front of his past. And blimey, it works. Unlike with those faceless bishie boyfriends.
To sum up the last one: Personality is far more important than the past. Past = the background if the painting. Personality = the subject of the painting. They work together, and past ALWAYS give some influence to the personality. However, don't overdo that, either: if your character's little brother snatched his/her stuffed bunny when he/she was five, most likely it DOESN'T give that big trauma.
Also, make sure that the past/background suits for the series. For example, a draenei that has lost all his/her family in a war against orcs is not unusual in World of Warcraft fan fiction, because the invasions of orcs were the reason why the draenei are at the brink of extinction. But a teenager girl in modern USA in the same situation is frigging rare and possibly even unbelievable, so you need far more carefulness to use this setting. At least remember not to put her just into a high school with happy face and like nothing was happened.
Give him/her JUST A FEW skills / special traits and stick on them.
Naruto did fine with just his Shadow Clone Technique, Rasengan, fox tricks and basic taijutsu in the Part I of Naruto series, and in Shippuuden he has obtained just few new tricks (that are mainly variations of the old ones). Also, Hyuuga Neji is one of the badassest guys among the Konoha Kids, though he uses just Hyuuga taijutsu and nothing else. Gaara is the Kazekage of Sand Village, and he uses almost solely sand ninjutsu. Making the skill palette simple enough gives a lot:
a) It's easier for the reader to follow the battles (or something like those) of the character, because (s)he can remember all the arsenal that the character can use.There is also the fact that people can't be even "quite good" in everything, because they often tend to use familiar ways to solve their problems. For example, in Naruto, if you are already quite skilled in taijutsu and not so good in ninjutsu or genjutsu, you probably are more willing to improve your taijutsu super good instead of learning average level ninjutsu or genjutsu. People tend to like develop their skills in areas in which they are already skilled. True Jacks-of-All-Trades are reeeeeaaaaallyyyyyy rare.
b) It's also easier for the author, since it's simpler to him/her to take control about the situations where the skills are used. Thus, (s)he can prevent situations like, 'Dammit! My character won that enemy in difficult way, because I forgot (s)he had that Hyper Skill n #42 that would kick that baddie's butt with no time!'
c) And, of course, it decreases Sueness. Mary Sues are famous of having that big arsenal of the skills that (s)he must carry a notebook to remember them all.
The thumb rule would be the following one: If you are not sure if your character is too powerful/skilled, give your character at most A COUPLE OF bigger skills. If the skill is really big, use one. If they are not that big, you can use a few.
Give him/her weaknesses that (s)he can't help.
'My character is really prone to get angered, but when needed, he can calm himself.' Oh yeah? Is hot-headness a weakness in this case? No, it doesn't, because the character can turn it out by his will. Don't give the character that proper control over his/her weaknesses - if (s)he can control them, they aren't weaknesses at all, just odd quirks!
Hint! The business are different if something external thing block or takes over the power of character's weakness. For example, a person that fears blood MAY rush to help at his/her badly wounded beloved, if the person fears the lost of his/her beloved a lot more than blood. Also, a hot-headed character can try to take over his/her feelings, if the Bad Guy is treating his/her beloved's life saying: "A wrong move and (s)he'll die!"
Don't call strengths weaknesses without reason.
Calling strength weakness is rather often used with Sues. Very common example is temperament: with Sues, hot-headness rarely cause problems to the character, but instead it helps him/her to express his/her feelings, tell truths at crucial moments, and attack on enemy more fiercely. Also, shyness is another common one: with Sues, it is usually used to highlight the heroine's interest to her crush and make her more cute, but it doesn't prevent her to act normally with other people.
That kind of traits work better as so-called double-edged swords: traits that serve both strengths and weaknesses. To make them work well, you should show both bad and good sides of that trait, both many times enough. Thus, you admit that trait is also a benefit to your character, but the character also gets his/her healthy portion of weakness.
Weaknesses are the ones that origins from him/her, not from the other people or surroundings.
All evil that is connected to the character are not a weaknesses. Being bullied, living in poverty or being harassed sexually is not the character's own weakness, because it origins from other people or environment: the other people bully and harass the character. Neither tragic past is weakness, it is just something bad that is happened to the character. Instead, evil thing can CAUSE and BE CAUSED by weaknesses: losing best friend in his/her past may make him/her unwilling to socialize with other people, and bullies may bully you character because (s)he is such a wimpy.
Normal human reactions are NOT weaknesses.
Your character is not a crybaby if (s)he cries in the funeral of his/her beloved: (s)he is just a healthy human with human emotions. Also, neither is that a weakness if your character gets angry at an annoying character that makes nearly all characters mad.
Make lists of the ALL strengths and weaknesses of the character and check that the lists are quite as long as the other one.
Or, if making a character that is total n00b, make the weakness list notably longer Don't use synonyms about the same trait, like "she is hot-headed, and has bad temper, and is easy to make angered...", it may make the results wrong! Neither too general categories, like (in fighting series) "she is good in battle". (WHY is she good? What all good traits make her good in battle?) Also, set the double-edged swords to both categories.
* Give him/her a trait of which other people can frequently poke fun!
This is not forced to use, but it decreases sueness greatly! Give him/her a trait that make him/her silly! For example, people make lot of fun about Edward Elric's shortness (and his overreactions about that) in Full Metal Alchemist. You can also make the character / character group to repeat a certain joke. For example, in Bleach, Rukia constantly draws poor and glittery bunny&teddy pictures when trying to explain something serious. Really controversial traits are often thought funny, too: again in Bleach, Chad is a hulkish brute that can collide with a motor bike without getting any bigger wounds, but he also is mad about cute animals and stuffed toys.
But remember to make the jokes like that they make THE CHARACTER funny, not the situation or the people attending it. For example, those famous panty shot scenes doesn't make the character her-(him-?)self funny, because it is usually an accident or caused by other person. The character her-(him-?)self is not acting in funny way in that kind of situation. (S)he is just a helpless victim. But, if you make the character to react very funnily in those situations (like fretting about that a guy sees her panties that are not the hottest fashion of the moment), it can be counted as making fun of the character.
W H E N W R I T I N G A B O U T H I M / H E R
If invented a notable bad trait for him/her, use it.
Many suethors list all kind of little flaws of their characters but never use them in the actual story. Practically it is the same thing that making no flaws to the characters. So, remember to show the worse side of your character, too! And frequently! You don't have to use ALL of his/her bad minor traits (like bad sense of taste or a little bad knee), but remember at least the biggest ones. Don't just think that your character is not perfect; show it to your readers, too!
Don't let him/her to hog all the cool scenes.
The reason why some fan fiction readers hate FCs (even non-Sues) is the fact that sometimes a FC is nearly always on the stage and leaves no room for the other characters. That is very common among Sues, too: they steal all the cool scenes and seldom let the other (original) characters to shine. To prevent it with your character, remember a thumb rule: If there is a cool thing to do, and some other character than your character can do it, too, let that another character to do it at least sometimes. And also arrange some own cool scenes to the supporting cast, too! The situation is different if you character is one of only characters of the story, particularly in original fiction (OCs' area).
Also, remember make him/her to do sometimes wrong decisions.
And again, it must be caused by him/her, not by the other people, the circumstances or his/her bad luck. For example, turning to the wrong street and ending up to attacked by street gang is not counted to be "true" wrong decision, because the trouble is caused by bad luck and not about the flaws of the character. Instead, getting provoked into a battle against someone too big and ending up to hospital after that is counted to be a trouble caused by him-/herself. Or saying to his/her friend things that (s)he later regrets.
Keep in your mind what your character really knows - it's not the same that the reader or the author knows.
Relating to previous one, it's usually really unrealistic if your character can mysteriously sense that (s)he can or can't trust on certain person, or be able to use his/her fresh new skill perfectly without anyone assisting him/her, or such, even if the author or even reader can see how to do it. For example, some Naruto Sues can immediately tell in Chunin Exams that they can't trust on Kabuto, even if Kabuto lured the main cast for good time, acting as good guy. Even if the reader knows that the character shouldn't trust on Kabuto (or any bad guy in canon), it doesn't mean that the character knows it. Set yourself into the point of views of your character and EXAMINE what (s)he really knows. Now you are allowed to think yourself as the character. Check for every piece of data that WHO REALLY can know that information (for example: your Naruto character probably can't know about the truth of Uchiha massacre, if (s)he is not some of the Konoha elders, Itachi himself, Sasuke or Madara, or someone that have got information from them).
Remember the character development during the story.
This is also very important to fan characters, but vital to original characters, since original characters have usually longer stories than fan characters have. Character development doesn't usually mean that the character gains more AWSUM POWAHS, but more importantly his/her mental growth and shaping of his/her personality. (S)he may learn to be more brave, or note that world is not that innocent or angsty that (s)he thought, or maybe (s)he learns forgiveness. Nevertheless, to allow character development, you can't start a story with a perfect character (or end it). Leave some room for growth!
Hint! Shuttling forth and back in the "perfection scale" can be a good tool, too. Zuko from Avatar: The Last Airbender is a great example of that. However, be careful about making it realistic.
* Choosing right words for his/her description can decrease Sue aspects greatly.
You don't have to be smooth or pampering when portraying you character. For example, doesn't it sound less Sueish to say, 'when annoyed even a little, he turns a real madman' than, 'he has a little bad temper'? Of course considering his/her true traits, people, overstating is not wise.
Also, many people before me have said that it's better to use mainly quite common words like "blue eyes and brown hair" instead of over-poetry stuff like "heavenly azure blue orbs and tasty chocolate locks". Personally, I think that it's okay to use poetry phrases A LITTLE. But just when the character really needs it.
Usually, when portraying a character, the impression is given from view of the the character him-/herself or by by-passers. Think of how the character could be portrayed in each case. Most people don't think they themselves are super pretty, but they may find some traits of which they are proud of, like nice shape or face or something. Usually, they think they are just plain, with both good traits and not-so-good ones. On the other hand, by-passers don't usually start to list all the details they see front of them, but rather give a "shape" to what they see: "There is a short woman that seemed like that the wind could make her fly... She was dressed in black from head to toes... Mostly, she seemed like that she didn't see other people..." See? Impressions, not exact details.
Also, I like to use poetic words when depicting a character that really is stunning in the opinion of the viewer (like, a guy in crush viewing his beloved)! However, when introducing him/her to more neutral audience (like, the readers), it is wiser to use neutral words for not giving a impression like, "(S)HE IS THE BEAUTY/PWETTYBOY, U MUST WORSHIP HIM/HER OR I BITES U!"
Sometimes the poetic terms can be in the crucial role. For example, in a novel series called Stravaganza, it was often pointed out that the heroine called Arianna had "pansy blue" eyes, because they were in the crucial part when revealing her true heritage - her mother's eyes were similar. If they'd be just "blue", it wouldn't be that notable detail in the identification process, since many people's eyes are just "blue".
* Is possible, move him/her background.
Though some Harry Potter fans claim that Lily Potter is a Mary Sue, most fans doesn't care about the fact because Lily doesn't appear in the book every moment. So, if you want to make super-cool character that won't be tagged as Mary Sue, move that character to the background. Then give the bigger scenes to dummier and less Sueish characters, so the more Sueish characters poke readers' eyes less. (Of course, all characters can't be moved to background. Some have to stand front.)
* Don't fulfill ALL his/her goals.
'Parents should cause children disappointments', states a parenting guide. So you can cause your characters. Give him/her a goal (s)he can't reach, like having hopeless crush to a person that can't care about him/her less. Thus, the reader can notice that the character is not able to make what ever (s)he likes!
N O T E S A B O U T F A N C H A R A C T E R S
Fan characters (like, a ninja character that is invented by you and that lives in the same world as Uzumaki Naruto) aka FCs have stricter rules in their creation than OCs (original characters belonging to no fandom). The reason is that they live in a world that you are not invented, and thus, you can't create the rules of the world by yourself. Also, Sue haters tend to be harsher with FCs than with OCs. So, to the fan character tips:
NEVER replace a canon character with your character!
Most fan fiction readers want to read about the canon characters, not FCs. In their opinion, FCs are meant to be just the tools that are made for support the performance of their favorite characters. Thus, the readers may get really upset if you suddenly switch their favorite character with your one. The thing becomes even worse if you make your character even better than the original one and thus overpower him/her. When that happens, the readers easily think that you are beating their favorites up.
The replacing DOESN'T always mean actual replacing by which that replaced canon character disappears from the story. In fact, more often it means that the new character hogs relationships, statuses, skills or anything like that that belonged originally to the canon character. For example, in Sonic the Hedgehog fan fiction, it is bad if you make a hedgehog that is even faster than Sonic, because it is stated that Sonic is the fastest hedgehog in the world. Also, in the same series, it's not wise to make your character to be the best friend of Sonic, because all Sonic fans know that Sonic's best friend is Tails.
You can make exception with this rule, if the whole idea of the story is to replace a canon character by the altered version of him/her. For example, if you want to think how Ranma½ turned out if Ranma were originally girl with poor fighting qualities and not a battle-skilled boy, you can replace male Ranma with your female FC that can be named either Ranma or not. Usually in this case, it's not wise to make the new character better than the original version. In fact, it is more fun to make him/her less skilled or good! Thus, the situations that were difficult to the original character are even more difficult to the new one!
In most cases, when making an FC, make sure that it can (s)he can exist in the world of the series without kicking an original character out or ruin their original relationships, statuses and stuff.
Avoid making your character overall better than most original characters.
As mentioned above, role stealing is what the readers can't stand. Relating to this, avoid making your FC notably better than most characters of his/her status. For example, if you are making a young Genin level ninja for Naruto fan fiction, mostly it's best to be sure that (s)he can't beat an average Jounin or even an average Chuunin level ninja with just his/her left hand, because most Genins in the series can't do that. Applies to the series that contains no fighting, too.
However, sometimes you may want to make a character that is stronger than most of his/her pals. You can do it, too, there is nothing wrong in that. But. You have to also know what is the real level of an average character and give a LOGICAL explanation where (s)he has gained his/her above average powers. Naruto isn't an average ninja, so if your character is stronger than Naruto, you need a GOOD explanation.
Hint! You can make your character the best one in a area that is not already taken over in the original series. For example, in Naruto fan fiction, it is totally okay to make your character the best singer of Konoha, because there is not mentioned already who is the best singer of Konoha.
Check the skill levels before comparing your character to a canon character.
I've felt a little funny when reading about a Naruto Genin FC that 'could beat Kabuto in a battle'. Isn't that a little over-powering? Kabuto is extremely skilled ninja that could put against Kakashi (that is Kage level judging by his skills). This kind of mistakes happens easily to authors that have no objective vision about the characters of the series. In many series, like Naruto, the main character is extraordinary skilled for his/her age or rank, and thus (s)he can blow up enemies that the normal people of his/her status can't beat. For example, there was a scene in which Naruto could make bad wound on Kabuto by his Rasengan. Don't regard the main characters as "normal cases" when creating fan characters in the fandom of those kind of series.
Avoid copying traits from canon characters.
If your Naruto FC is faints when seeing his/her crush (like Hinata), owns a dog looking like Great Pyrenees (like Kiba) and was originally strict with rules but changed when his/her friend died heroically (like Kakashi), there is a lots of stuff to clean up in you character. Don't ape the aspects of the canon characters and stuff them into your one! It is stealing! But don't be afraid to use general aspects that appear in the original series, too. For example, you still can make a shy character for a Naruto fan fiction, even though there is Hinata that is shy, too. However, don't make him/her behave exactly like Hinata: not all shy people pass out when seeing their crushes! Again, observing real people is golden.
Keep the canon characters IC (=In Character) when writing about them.
Many Sue haters blame the suethors about the fact that their Sues make the canon characters behave out of character. For example, a Sue can make an evil character to act like a little puppy when she is close. Personally, I see that all OOCism with canon character doesn't derive just from using Mary Sue with them (OOC = Out Of Character). Most suethors are quite inexperienced writers, so they can't handle canon characters objectively, either. That may cause illusion about that Mary Sue turns other characters OOC. Was the reason for the phenomenon what ever is was, make sure that you make all canon characters you use IC. Thus, you can prevent yourself from these complaints!
Be warned about Canon Sues.
There is a funny fact that many writers don't often think. The fact is that you can turn a character into Mary Sue, even if the character is not invented by you and even if (s)he isn't originally a Mary Sue. For example, there are some odd Hinata fan fictions where Hinata has gotten mystically heaps of self-confidence and can act like a real rebel. There is also Harry Potter fictions where Hermione is not a nervous book worm with messy hair but an laid-back and über-sexeeeeh heroine. In other words, Canon Sueing is over-polishing the image of a canon character (that is often a favorite character of the author). The best way to prevent Canon Sues is to make careful research about the character and make sure that you show him/her in the way that (s)he is shown in the original series. Wikis of the series and the original manga, anime, books, movies, and tv shows are your friends.
Wish from the Audience:
N O T E S A B O U T O R I G I N A L C H A R A C T E R S
Original characters (a character that is invented by you and that lives in a world/story setting that you are invented) aka OCs are easier to make non-Sues than fan characters, because you can set the rules of your story world by yourself. Can your character fly? If you have decided that flight is a normal skill in your storyversum, it's totally okay to give that skill to your protagonist, too. Plus, Mary Sue haters are not as prone to attack on OCs than on FCs.
However, even if you have more freedom with OCs than with FCs, Sue danger still exist. You can't justify all Sue traits by saying that that's your world and your rules. I try to collect here rules that are good to remember especially with original characters.
What ever creature (s)he is, avoid making his/her nature too perfect.
Most characters (except mindless monsters, animals and such) are based on humans and human nature, even if your characters were aliens or fantasy creatures. Humans aren't perfect creatures, as we well know. So, to ensure that the reader can feel that your character with brains is believable, give him/her also human personality flaws - something that human-like brains give. Every fantasy/scifi creature with brains have some human traits, and human nature is not least of them.
If you still want to make a perfect personality (like a god, a goddess, an ideal human, a perfect android...), avoid using that character as a character that the reader should pay his/her attention much. For example, usually it's quite good idea to use super-powerful, super-nice and super-wise character as a tutor of the hero of the story; thus, the reader pays attention to not-so-perfect hero and doesn't start to regard that tutor too unnatural creature. The reader may also think that the positive image of the tutor may come from that the hero looks up his/her tutor.
...is mentioned earlier in section When writing about him/her. This is VERY IMPORTANT especially for OCs, because OCs have often longer stories than FCs and have more time to develop. Next issue.
Set clear rules for your world and stick on them. Avoid adding extra laws later.
From very start, try to make clear in your head what all traits your (protagonist) character has (that moment) and, the most important, explain why your character has that arsenal that (s)he has (if you are skilled writer, you can slip from this rule, if you understand why it exists). Is it due his/her race, job, genetics, training? Is here also other characters with similar skills? Or better skills? Avoid surprising readers with loopholes or deus ex machinas and make the rules of the game clear - and most preferable, keep the rules simple. This requires planning in advance, but it makes your story more believable. You don't have to reveal all the things in the very start (think about start of Full Metal Alchemist, for example), but soon enough to let the reader to know what the character can really do in crucial fights.
This thing is often something that bugs me in shounen manga. Often, they have first clear laws in their worlds, but alas, when the authors start to lack ideas, they throw in more laws. And it makes the story suffer. Examples of that are, in my opinion, Sharingan in Naruto and almost all the stuff in Bleach.
Still avoid making him/her too special...
"Errr... she can fly even if other people in that world can't?"
"Because she is the last one of her kin!"
"...and she can see instantly who is the culprit?"
"Because she is trained by the Hermit in the Mount Awsum!!!"
"And use huge laser destroying all bad guys and resurrecting all good guys with no sweat?"
"Because she is the Chosen One!!!!1111oneone"
...just use your brain. Even if you give "logical" reason to all odd quirks in your character, even if you shape your world like that the skill can exist, it is really silly if your character has tons of special skills that normal creatures in his/her world (possibly in his/her position) lack. As said earlier, DO NOT STUFF TOO MUCH SPECIAL STUFF TO HIM/HER. Even if (s)he is the protagonist.
L I N K S T O O T H E R A N T I
M A R Y S U E T U T O R I A L S
Here is some links to other helpful Anti Mary Sue Tutorials and such.
* The Universal Mary Sue Litmus Test. A famous Mary Sue test. Quite harsh but effective one, though don't read it as a Bible. And remember to read the instructions to get quite reliable results!
* anti-mary-sues.webs.com. A helpful site for discussing about definition of Mary Sue and tricks to avoid them. Has also own group in DeviantART: Click.
* How to Make a Character by lonestranger. He said many things I couldn't find words.
* Character Cliches to Avoid by GMYuna. Helpful list.
* Addi vs Addi by Addi-Pink-Power. Comparison of a decent character and a Mary Sue.
That's all. Have fun with character making! <3