Common Mary Sue Traits



""Im good at too many things! WHY CAN'T I JUST BE NORMAL? IT'S A FUCKING CURSE!""

- Ebony Dark'ness Dementia Raven Way, of My Immortal

While Mary Sue is too nebulous to be judged by any hard and fast standard, certain traits have become surprisingly popular. In an effort to make their characters more attractive without having to do the leg work of natural character development, the authors just add some of these superficial traits to their character. Below are the ones that the collective unconscious (so to speak) find especially attractive and end up incorporating into their characters with regularity.

With the way the word has mutated over time, a great many people just end up labeling any character overdosed with these traits as a Mary Sue regardless of her importance within the story. That's not necessarily true. Even if a character has quite a number of the traits described below, Mary-Sueness can still be averted by a good enough explanation for why they're there. Some female characters may seem over-powered and a bit "too good to be true" on paper but when placed in context they can be well-developed, three-dimensional characters. It's when a trait exists more to make somebody stand out than to develop them as a character that it starts going into Mary Sue territory (unless it's Played for Laughs). Alternatively you may feel as if the writer is frantically trying to justify a trait to themselves and the reader.

Sadly, a lack of these traits does not automatically mean the character isn't a Sue: see Anti-Sue and Suetiful All Along.

This article will concern itself with gender neutral and female traits. For (the few) male-exclusive variants, see Marty Stu. For a litmus test that draws on much the same source material, see here.

Personality

 * What personality? In these cases, it's fairly blatant the author is just writing the character for amazing stuff to happen to instead of a character that actually exists as a person. Obviously, this is only a Mary Sue trait if what happens gives the character special powers, fantastic romances, or somehow lets her be a big damned heroine; otherwise it's just another faceless first-person perspective.
 * The personality of a Mary Sue, if she has one, is not nearly as important as how other characters react to it. No matter how shy or socially awkward Mary Sue is, other characters will be drawn to her and (for some reason) prefer her company over that of anyone else, all of her ideas are brilliant, all of her jokes are funny, any insight she offers (no matter how obvious it may seem to the reader) will be an amazing breakthrough that no one has ever thought of before, people (unless they're being portrayed negatively) will trust her immediately (or learn to trust her very quickly) and feel more comfortable talking to her than to anyone else (even their own family or their significant other) even if she hasn't done or said anything to make them feel that way about her.
 * If another character critisizes Mary Sue, the author will usually have written that in for the sole purpose of making that character look bad.
 * Mary Sue doesn't have to actually do anything to be considered a good person, she just is good and by extension anything she does is good and even when she does nothing she brings more good into the world simply by existing than any other character ever could. Goodness just seems to seep out of her body like radiation.
 * If there is a personality, it's who the author wishes they could be, never who they are. While this is a regular feature in most original characters, Mary Sue takes it to the extreme.
 * Highly persuasive, regardless of the actual content of their conversations. Everyone finds her opinions are just better than their own - even when they're usually stubborn bastards. This is especially likely in an Author Tract.
 * Friend to All Living Things. It's becoming gradually less common as authors catch on to the Mary Sue Classic framework.
 * Is either brave and cheerful (despite her past), or unnecessarily mopey and depressed.
 * Incorruptible. In fact, unaware of the possibility of temptation.
 * Occasionally a complete asshole, especially when she's supposed to be all of the above. Nobody will call her out on her abrasive, casually abusive behavior. Plus, strong badass characters who would normally rip someone's spleen out for looking at them cross-eyed are instantly cowed and become meek, spineless Wangst factories as soon as she "puts them in their place."
 * Her "major flaws" will be stubbornness and a bad temper. These will only ever help her, never hurt her -- because she's always right, so whatever cause she dedicates herself to with such stubbornness will be a good cause, and whoever she loses her temper with will deserve it.
 * Sometimes they'll mess her up once so she can learn an important lesson. And then they'll help her for the rest of the story.
 * Don't forget clumsiness. But not your average clumsiness, she will only be clumsy as the plot demands and/or when the author decides she needs to appear more flawed yet endearing
 * I Just Want to Be Normal: Being super awesome is a curse.

Skills

 * Inexplicable and/or poorly defined abilities in general, especially if they play no factor in the plot after their introduction (not even as a Required Secondary Power) and are only there to make the character seem even more awesome.
 * Regardless of what skill level the canon characters have established, she might just simply be better than them, often in ways that do not make sense. See also: Always Someone Better, God Mode Sue.
 * Not to mention that if she isn't already skilled at something, she'll pick it up in a fraction of the time required.
 * That's if she even needs to learn them at all.
 * Magical powers similar to what the other characters have, only with the limitations removed.
 * A perfect singing voice. Most often shows up in Mary Sue Classic. This died out for a while, but is returning due to the popularity of pop divas.
 * Extreme proficiency with an instrument of her choice.
 * And if it's a Song Fic, she'll possess the ability to compose her own lyrics and songs. Of course, they're NOT her own lyrics, they're somebody else's.
 * She tends to not have normal sex, but the most mind-blowingly divine sex ever, regardless of how experienced she actually is.
 * And her lover is often a Draco in Leather Pants quickly Heel Face Turned by her vagina.
 * Speaks several languages fluently. This can vary depending on the setting, of course. A modern-day diplomat is expected to know at least one or two other languages, but a 14-year-old peasant girl in Medieval Europe shouldn't speak Japanese and Hindi fluently. It's much worse if it includes animals. Bonus points if an alien lands in her backyard and she can communicate instantly (provided it doesn't speak the language already).
 * The most common second languages are probably Romance languages (because they sound awesome), Japanese (for the otaku), and Lakota (many Sues are of American Indian admixture, but never more than half).
 * Skilled in a type of martial arts in a setting or with a backstory that doesn't allow for it. Not regularly skilled either; she could kick the ass of the resident ninja of her choice.
 * Just random magical powers, such as telepathy in a universe where it's never even been mentioned.
 * Or in a universe where her ability is naturally impossible to have these abilities, say ... bog standard real life?
 * Absurd natural athletic ability - she can run like the wind without ever having worked on her running, and has impossibly high acrobatic skills.
 * And with all this - don't expect the Green-Eyed Monster to show up. Envy appears in the Mary Sue's life only as a means of angst, and so does not appear just because the Mary Sue has everything.
 * Alternately, anybody who does get jealous is a bitch and is wrong. This is typically a single other character and may be Die for Our Ship or for other reasons.
 * Mary Sue always has excellent fashion sense, even if she's meant to be a ruff-and-tumble, Tom-Boy type who doesn't care about that sort of thing, she will always look effortlessly beautiful (Unkempt Beauty) and other characters, often males, will frequently talk about how they like that she isn't as high maintenance as other girls (if she has a female rival they might mention her specifically.)

Physical Appearance

 * So Beautiful It's a Curse™. While being attractive isn't a qualifier of Mary Sue (who wants to be ugly?), it's a bit excessive to try and play it as being some sort of disadvantage. Alternatively she may only be Suetiful All Along. In an Anti-Sue, this is reversed into a hideous monster. Regardless, her astounding beauty (or astounding lack of it) will make her stand out from the crowd - or so we're constantly being told.
 * Unusual hair and/or eye color relative to canon is another common characteristic of Mary Sue. Alternatively, these features may be amazing in other ways - shining and shimmering eyes, or Anime Hair in non-Anime fandoms.
 * Rapunzel Hair is also common.
 * Another variant is Kaleidoscope Hair, where the Mary Sue can change her hair color.
 * Note that White Hair isn't really considered all that unusual in anime-based fiction. It only becomes Sue-ish if it makes her special.
 * More important than colour is highlights. Of course hair dye is nothing special, but somehow Sue's streaks are not only a colour completely different to the base, but also natural. Nature allows some leeway here - blonds with dark roots aren't unheard of, but that's not what Sue is after.
 * Similarly, these "natural" highlights are often a color such as blue, pink, purple or any other color that doesn't occur naturally in hair outside anime.
 * Kaleidoscope Eyes. Seeing it in text is practically an instant Mary Sue qualifier.
 * She might have a waiflike figure, so slim and delicate... and yet her breasts are perky, supple D-Cups (because obviously, otherwise boys won't appreciate her personality), totally disregarding the fact that in reality, the slimmer you are, the smaller your breasts are likely to be (though there are real-world exceptions, a few even natural). These breasts never get in the way, or make running difficult, or sag. If height and weight figures are given, expect it to violate physics (unless she's made of Styrofoam or something).
 * This particular trait is magnified if her role in the story has her doing things that would require a lot of upper body strength and therefore bulk, such as wielding a sword or fighting hand-to-hand. It's magnified even more if there are other female canon characters with similar roles who are built more like female mixed martial arts fighters. Having one lone waifish and delicate young girl in that group because the author thinks muscular women are gross-looking and to have that lone waif fight just as well or better than someone with more muscle mass despite her physical limitations is a bog standard Mary Sue trait.
 * Mary Sue is also never depicted as putting too much effort into maintaining her body, she may get an Adrenaline Makeover, but she never has to diet or exercise (she may exercise for other reasons, but never just to maintain a certain weight or to look a certain way) or use any cosmetic products, she just naturally looks (the authors idea of) perfect and usually doesn't understand why everyone is so impressed by her effortlessly flawless appearance.
 * Also, no matter what she's been through, Mary Sue will never look ugly, the worst she'll ever be reduced to is Unkempt Beauty and even if she is somehow injured and scarred or handicapped the scar will always been a cool looking, Bond villain type scar that serves as more of a decoration than anything else and, when she overcomes the handicap, she will be just as amazing as she was before getting injured (or better.)
 * Like wise, if Mary Sue has a birth mark, it will be in a significant shape (heart, half moon, etc.) and never in a place that compromises her beauty.
 * She'll often wear revealing outfits with tons of gems, fishnets, Frills of Justice, and other extraneous details, even if it may be difficult or impossible to find such an outfit in the world (or be well outside of her realistic price bracket). Such flashy outfits will likely be just too impractical to wear in Real Life.
 * Similar to the above, she will often wear special clothes even when the rest of the cast is supposed to be in some form of uniform.
 * Alternately, she will wear a uniform that resembles the standard one that other characters wear, but it will be customized, and in a skimpy and impractical sense. For example, if the uniform includes a skirt (or even when it doesn't), Sue's skirt will be skin tight and extremely short, and will usually be paired with thigh-high fishnets.
 * Purple seems to be popular. After all, Graceful Ladies Like Purple, Purple Is Powerful, and Supernatural Is Purple. This applies especially when the canon characters are a Five-Man Band color-coded with red, yellow, green, blue and white/silver/black/pink. Gold is about the second most popular.
 * In text, massive descriptions of their clothes, or links to images of their outfits. Bonus points if it's designer clothes in a situation where it would be unlikely and/or expensive for her income.
 * Descriptions of her looks are usually overly-detailed and distinctly violet-hued. Because saying she's slim with long black hair and blue eyes only tells you what she looks like. Saying she's a delicate, willowy goddess with flowing tresses that shimmered onyx like the feathers of a raven and sparkling cerulean orbs that shone like the ocean and radiated with femininity tells you she's special.

Accessories

 * Magic jewelery. It might be used as a Green Lantern Ring to justify her abilities.
 * Exotic weaponry in a setting where she shouldn't have access to such. Usually, the question of why the law enforcement allows her to carry it doesn't come up and nobody seems to find a girl carrying a large sword intimidating. Bonus points if there is no explanation for where she keeps it.
 * A katana. Now it's not impossible to have a katana outside of Japan anymore, but when it's because Katanas Are Just Better (especially in a place they either shouldn't exist or would be technically useless), you've got Sue-ness coming on. Two katanas is almost always a dead sure sign.
 * Sometime they'll use guns instead, especially if the setting doesn't usually have them, and in which case they're almost always revolvers. Or a minigun.
 * Or if they're particularly into firearms, just check the list of Rare Guns. (see Desert Eagles) Often as lavishly described as the outfits.
 * If she has her own transport, it will always be cool and expensive. Sometimes she has her own Time Machine - even worse if it's based on something from a different canon.
 * She may have access to a Humongous Mecha in a universe that lacks them, or only hands them out on a case-by-case basis.
 * The web exists everywhere for her-- she can whip out her laptop anywhere and have access to both our normal internet and the local internet of whatever world she lives in. And use it to hack toasters and the Pentagon. Additional Sue points if her laptop displays an unnaturally long battery life. (i.e. the battery never runs out, even while adventuring in places where there's no obvious means of recharging it, such as forests, deserts, or mountains.)
 * If the Suethor's favorite character has a one-of-a-kind weapon, Mary Sue will usually have a previously unheard of identical weapon. The trait is reinforced when Mary Sue's weapon was handed down to her through generations, especially if, in canon, no one knows where the original weapon came from. For example, if Sephiroth has the Masamune, the Mary Sue that has been foisted on him in a particular story will have an identical weapon called the Murasame.

Canon Character Relationships

 * Some Wish Fulfillment with a character you think is hot isn't that bad. But Mary Sue seems to grab their attention straight away. Even if they already have a stable love interest in canon, that relationship will be treated as either non-existent, or the couple will be split up in some way.
 * Bonus points if the love interest stands aside or sacrifices himself/herself so Mary Sue can be happy, or is twisted into a hateful person to justify Mary Sue breaking up the canon couple.
 * Or perhaps Mary will be introduced as the canon character's New Old Flame and this is their rediscovery of each other, though it's never really explained why they split up in the first place if they loved each other so much.
 * Turns out to be the offspring of a canon character. Made worse if that character would have been too young to have the Mary Sue, is gay/asexual, or perhaps is just physically incapable of it. For added Wangst, it's the villain.
 * She may be related to a canon character in some other way. This can be the explanation for a Copy Cat Sue. And why spend chapters explaining why the heroes accept a total stranger into their midst so readily, when they can just shout, "Luke, I am your sister!"
 * Kid From the Future may explain away the 'young' part, but not much else.
 * If It's You It's Okay can explain the "gay/asexual" part. Alternatively see Mister Seahorse which only makes said Mary Sue more unique.
 * Even the characters who don't have sex with her give her more heed than they normally would. Characters she likes can't stop talking about her beauty and power. Characters she doesn't like can't stop making themselves look bad by insulting her. There may be just "something special" about them, with no particular reason why anybody would think that. In the worst-case scenarios, they pay no heed to their own responsibilities or lives, only to Sue.
 * Bonus points: the disliked character behaving badly toward the Sue eventually sees the "error" of his/her ways and grows to love Sue as much as everyone else does.
 * More bonus points: the bad behavior and treatment of the Sue by disliked characters is portrayed as jealousy.
 * Previously-established personalities change in reaction to her. Arrogant gimps may admire her for everything. Sweet, mild-mannered characters (that she and the author don't like) insult and degrade her. A leader with responsibilities pays attention only to her. Young, reckless characters who would never settle down just yet will become totally reliable. Evil characters follow her around like a puppy or seem uncharacteristically obsessed with her. Extremely competent characters become stumbling buffoons who require her help to do anything. The characters in general just seem unnaturally focused on her, positive or negative.
 * If she's inserted into a story from before a canon character turned out to be evil, she will be the only one who suspects him.
 * Or if the canon character's evil was the result of a Face Heel Turn, she will be the one who prevents this alignment switch from happening.
 * She gets special treatment in-universe. The classic example is the Harry Potter "exchange student" fic where a sixteen-year-old American girl enters Hogwarts as a sixth year, is immediately given a spot on the Quidditch team and doesn't have to wear the uniform. Chances are good that Sue will be making all the calls that should be somebody else's prerogative; she's probably the one telling the Sorting Hat which house she's going to be in.
 * May serve as a Manic Pixie Dream Girl if her love interest is especially dark, brooding or troubled. She "cures" him of that, often at the expense of his characterization.
 * She may have relationships of some kind with multiple major canon characters. For example, she's the secret daughter of A who gave her up to be adopted by B's parents, making her his sister, and she goes on to have a passionate affair with C, remaining friendly with him even though she goes on to marry D, and she's E's best friend, F's closest advisor...and so on.

Story Elements
"Abusive Parents - all too often because she's special in some way, and not just because her parents were assholes.
 * Mary Sue is always on the Spotlight-Stealing Squad. Without her, there would not be a story.
 * If she has any flaws intentionally written in by the creator, expect them to be Informed or not really flaws to begin with. Bonus points if they're genuine flaws that would actually be pretty awesome were it not for their drawbacks (e.g. substance abuse, nymphomania, etc.), and of course the drawbacks will never be shown.
 * Clumsiness is a common "flaw".
 * Which tends to manifest itself only a few times throughout the entire story, like the author saying, "No, she's not a Sue. See, she has flaws!"
 * She's The Chosen One. Even if the canon hero is already The Chosen One, she either 'shares' the position or just steals it away from them.
 * Or she might be part of the same specialized species/organization as the hero. See Sailor Earth.
 * Alternately she is "destined to help the destined one fulfill their destiny" which pretty much means do all the real work except for the final blow so the prophecy isn't technically wrong.
 * She is often around the age the author is, or just looks that way despite being Really Seven Hundred Years Old so that she can be wise and leaderly. This doesn't have to be bad (there are many settings where it's acceptable) but when you start seeing hardened military officers that are 16...
 * Sympathetic Sue has an unusually Dark and Troubled Past to the excess, but other subtypes often have them too, just to emphasize how brave and special she is to live through it. This past is never really a point in the story, just dropped casually into the conversation to get attention. Alternatively it's written badly owing to not doing much research. How much she Wangsts about it is usually out of proportion with how bad it really is.
 * There are several popular methods:

Heartwarming Orphan - Plane crashes and car accidents are increasingly common ways to make her feel responsible, without actually doing anything wrong.

Parental Abandonment - Not just because it's a baby and babies are expensive, messy and smelly and the parents didn't want it. There has to be a SPECIAL reason for that abandonment - this is Sue, after all.

Rape as Backstory - Most notable when it's given just as a cursory excuse for... well, whatever."

"Sue: I'm sorry I Just Shot Marvin in the Face.
 * She might be a Blithe Spirit and reform an entire population center of its negative qualities. Bonus points if this involves The Power of Love, The Power of Rock, or (to paraphrase Lisa Simpson) being "[...]rebellious... in a conformist sort of way".
 * Perform a Heroic Sacrifice as a way to prove that she's Too Good for This Sinful Earth. Bonus points if the story goes out of the way to ensure she doesn't leave an ugly corpse (whether it be by a method that doesn't involve external physical damage or by her body not being recovered).
 * More bonus points if it turns out to be a Disney Death.
 * She might turn out to secretly be half-human, half-(insert species here). Or maybe just full (insert species here). Elf is extremely common, but any sufficiently human looking, "pretty" race will work. For added points, make her feel outright shame because she's not human even though, if anything, it only makes her more beautiful and/or powerful.
 * Or maybe she's a Cute Monster Girl. Bonus points if this does not mesh with canon (i.e. canon dragon girls have heavy scales, flat chests, large talons for hands/feet, and are just flat out monstrous, but this character is just simply human with dragon wings, tail, unobtrusive horns, and a couple random scales on her shoulders and midsection).
 * Similarly, if she's half-cat or dog, the only physical proof of this is that she'll have cute ears and a tail.
 * Also common is vampire-anything (like a Half Vampire), with no discernible monstrous attributes or drawbacks, which often leads to great amounts of Purple Prose or a Copy Cat Sue syndrome.
 * In some cases she's somehow half-human + half-elf + half-veela + half-angel + half-saiyan + half-God-like ridiculous hybrid creature. Bonus points if one of these races does not even exist in the story's canon, or if the end result would be illogical by definition (i.e. a half-demon/half-angel).
 * If the character is already a furry, they'll typically be some incomprehensible hybrid, a rare or little-used (always pretty) species, and/or have wings regardless of species.
 * Bonus points if whatever species she is makes no sense in canon. Sure it's okay in a fantasy book, but in a regular fiction book there probably shouldn't be any elves walking around.
 * Redeems the villain through her overwhelming goodness. Might be through Redemption Equals Sex (bonus points if it leads into IKEA Erotica). Even more bonus points if the story decides to mention that this is her loss of virginity. Yet more bonus points if the villain comments on how awesome she is in bed despite said virginity.
 * As she gives the most awesome, mind-blowing, divine sex ever, it obviously comes with super-redeeming powers. Yet, if the villain isn't her choice love interest, her love interest of choice will be better at it.
 * Is a princess. Everything's Better with Princesses, after all. Bonus points if she grew up as a peasant (or equivalent social class) and only just discovered this during the story. Of course, in any case, it will be a position of high opulence and little actual responsibility.
 * On a similar note, the Changeling Fantasy is popular enough in its own right without ever involving Rags to Royalty to begin with. It's certainly advantageous to the writer to have a set of cruel parents that can be replaced with ideal ones.
 * In fantasy canons, she can break the Rules of the World at will. Often, nobody will even be surprised.
 * If she ever does anything wrong, she's both instantly remorseful about it and Easily Forgiven by those she wrongs.

Marvin's Friend: It's okay. I never liked him, anyway."


 * She will often suffer from Special Snowflake Syndrome, having some trait or backstory that sets her apart from her race.
 * This can be taken to the point of being from another setting entirely. It's no coincidence that many of the most notorious fanfics are mega-Crossovers.
 * Sometimes, the Sue has only one supernatural power: being The Chosen One. Her chosenness makes her critically important to the world, but since she has no other godlike powers, she will spend most of the story being kidnapped (usually by a villainous love interest) and/or otherwise victimized. This is becoming more common as writers catch on to God Mode Sue, since it allows her to continue stealing the spotlight while still avoiding the "god mode" label.
 * Will often be either of the author's ethnicity, an ethnicity the author wishes to be (often Magical Native American), or both. Not bad by itself, but can lead to Unfortunate Implications, and often occurs in cases when it's not even likely.
 * In fanfiction at its most unoriginal, an Author Avatar is sometimes just inserted into the story as it happened (the Tenth Walker is to The Lord of the Rings as the American exchange student is to Harry Potter) and has basically no effect on the plot -- she's there to either elbow aside each of the canon characters in turn and take over the plot points they were responsible for, or even more boring, just stand around and watch them do their thing, thinking all the right thoughts to show what a good judge of character she is -- maybe with a romance with a canon character or an occasional Fixer Sue moment thrown in. Reading these fics is like experiencing the original work with a thirteen-year-old fangirl talking in your ear.
 * Mary Sue is also often written into fanficiton as a character that just happened to not be shown in the actual movie (book, graphic novel, etc.) but who was really supper important behind the scenes.
 * You remember that dark, brooding, emotionally closed off character who always had his guard up and never confided in anyone? well, little did you know, he had a best friend/relative/therapist/love interest who was the only person he ever felt comfortable talking to and he told her all of his hopes and dreams and secret motivations.
 * You know that lone vigilante who saved the day and then disappeared into the night? well, little did you know that he had a friend/love interest who was secretly by his side through it all and even helped him to execute his plans/ helped him come up with all his best ideas/ was his whole inspiration to be a hero in the first place!
 * Writing an OC who has a connection to an existing character isn't necessarily bad but must be handled delicately; too many fanfiction writers make the mistake of making their OC solely responsible for everything that was good about a particular character or putting her behind every significant cannon event.

Names

 * May be named after the author in some form. Becoming less frequent as people catch on to the Litmus Tests.
 * The more common practice is to give the Sue a name that the author really, really likes. As in, wishes it were their own name or the name they'd give to their firstborn. Names like Raven, Hunter, Samantha, or Sam are really popular for this.
 * May have some overly long, complicated, usually Meaningful Name that relates to her abilities or personality - whether this is usual in canon or not.
 * Her name is sometimes a gemstone, a flower, celestial bodies, (i.e. Luna, Stella, Celeste) or a pretty color (e.g. Violet, Sapphire). With Emo-Sues, her name is something spooky, mystical, or related to darkness (e.g. Raven, Trinity). Of particular note, Serenity seems to be a cliche often finding its way into parodies.
 * May have an unusual spelling of a normal name, like Krystal or Syndi.
 * Maybe they have a generic Japanese name like Hikari or Sakura. Bonus points if it's a decidedly non-Japanese setting.
 * The reverse can also occur in other cultures, when people are given "exotic" English words for names. Often results in name which doesn't mean quite what the author intended, due to the large vocabulary and connotations attached to many supposedly synonymous words in the English language.
 * And of course the same can apply to any other language that the author thinks is cool.
 * It is not uncommon for a Sue to have a combination Japanese/Western-type name, e.g., Hikari Rose Nightshade or Sapphire Morimoto. While such names are not unheard of in real life, they are practically a six-foot-high neon sign flashing I'M A MARY SUE when it comes to fanfic.
 * Above all, the name is inconsistent within their particular culture. So you get cases of a small isolated village where Bob and Andy are lusting over Serenity Jasmine Sunrise Snapdragon.
 * Which raises another point: if standard western names have 3 parts--a first, middle, and last name--expect her to have four or more. For example, Robert Charlie Smith and Mary Jane Jones will be friends with Raven Fire Trinity Helena Insanelylongandhardtopronouncelastname.
 * If part native, expect one of a list of native names that probably don't mean what the author thinks they do, aren't really native, or are the names of tribes.
 * Her name may be an awkwardly feminized version of the author's favorite male character's name. For example, Final Fantasy VII fanfic is littered with Sephiras, Sephirothas, Sefiras, etc. There has even been a Sephora.

Presentation

 * A massive amount of time gets spent on describing her every feature in her introduction. Obviously, most canon characters are already well-defined to the reader whereas the new character needs an adequate description, but if it spends paragraphs, continues cropping up throughout the story, and includes detailed appendices on every little detail, just abandon all hope.
 * She gets Purple Prose (usually with heavy Fetish emphasis) while no other character (canon or otherwise) gets it. Whereas her love interest extends his hand out to her, she slowly but confidently raises her slim, tender, yet dexterous left hand that has a ring on her index finger to hide a small birth mark, shifting her weight to her front stiletto adorned foot and causing her long, flowing aquamarine hair done with two front tails to ripple and her supple yet firm right breast to shift ever so slightly, rubbing against her slightly loose but supportive black lace bra and causing her heart-shaped face to gain a slight bit of blush underneath her sparkling emerald eyes.
 * Relatedly, many things about her are described as "[adjective] yet/but [adjective that often comes into conflict with the other adjective]".
 * In visual media, the camera just can't stop staring at her. Every angle is seen several times and her every action gets a heavy emphasis with close-up shots galore. Other characters don't get to be in the frame alone if it can be helped.
 * New words get made up to describe her. She isn't just fantastic, she's megariffic!
 * Whole passages seem minimalistic, as though the author knows what's going on and only wrote the parts that he/she wanted to fetish-obsess over.
 * Pressing concerns of the actual story such as a villain who's actively trying to take over the world, aren't even addressed because everybody is too busy taking an interest in the new girl's life.
 * Alternatively, major plot points (that aren't solved by the new girl) are done entirely off screen. If the handsome yet evil character walks in and explains that he has seen the error of his ways, confronted his evil father, killed The Dragon, and found the seventh and final MacGuffin all in one sentence and nobody seems to really care because Princess Doctor Professor Saint Serenity Jasmine BelleSunrise Snapdragon the Ninja Pirate Zombie Robot, KBE, Esq., wasn't directly involved, that's not a good sign. (also, a pretty stupid thing in itself)
 * When the character is off screen, if ever, the other characters are still talking about her, taking it as a chance to speak "honestly" about the new girl. If they like her, they sing her praises; if not, their dislike will be taken as jealousy, as her "haters" will only talk about petty issues (Sue's background, perceived promiscuity, etc.), and not genuine gripes (massive attention whoring for starters).
 * The story is often told entirely from the POV of the Mary Sue, sometimes in first person so the focus can never shift away from her.

Author Investment in the Character

 * The same character--either literally the same character or the same in spirit--tends to appear in all of the works by a particular author or artist because they identify so closely with the character.
 * The author takes personal offense at any criticism of the character or story, no matter how well-meaning or justified it is.
 * Bonus points for an overblown ego behind it.
 * The author may get upset when she sees her favorite character paired with anyone but her OC.
 * In extreme Small Name, Big Ego cases, the author will create a fan club for her own Mary Sue and/or aggressively ships the Sue with a canon character and makes a fan club for that.
 * The author/artist has a massive gallery of art exclusively of the character. A few illustrations to give an idea of what a character looks like is a good idea. Over a hundred illustrations of a single OC is an obsession.