What's a Mary Sue?
Notes on appearance:
1. She is beautiful.
This includes all the right curves. Breasts in particular are a very important part of her appearance, and must be described at some point (especially if the story will contain sex).
She is generally either very tall or very short, whichever looks more appealing with her male counterpart. However, she is always thin.
2. Hair and eye color, as well as skin tone, are often described in heavy detail, as in a police report.
Often, her hair is an unusual color, such as the favored red or blond. If it is not, and even if it is, there are adjectives such as "shining," "lustrous," and "silky," or adjective phrases such as, "sparkling like the stars in the night sky."
Eye color description uses colors like green, blue, violet, gold, or red. Sometimes, the author compares the Sue's eyes to gems, as in, "her brilliant emerald eyes," or whatnot. Her eyes can also be "catlike," "shimmering," "flashing," and "the window to her soul." In the worst-case scenario, they can change color depending upon factors like her mood or usage of her special powers.
Mary Sues are always very pale, or perfectly tanned. There is no happy medium. Pale Sues seem to be more common, with adjectives like "creamy," "ivory," "snowy," or "alabaster." Tanned Sues use "caramel," "mocha," and other food words to describe their complexions, though they may sometimes say "sun-kissed" or just "tanned."
3. She may have markings related to her past. These can be scars, tattoos, or even some kind of makeup, but rest assured that it is somehow relevant.
4. If she is another race, like a youkai, angel, or vampire (to name only a few), she has to show this outwardly.
If she is a youkai or hanyou, this includes, but is not limited to, animal ears, a tail, claws, catlike pupils, and/or fangs.
Her eyes, if she thinks it will make her race more obvious, will be gold, silver, or red.
She may, if it is appropriate to her race, have wings. If they are feathered - and they almost always are - the feathers will be purest white, deep black, or will shimmer with many colors.
Notes on background:
1. She has ties to a favorite canon character.
She can be someone's relative, friend, rival, or a coworker or colleague.
2. She knows a canon character from the past.
Usually, she is a former lover or an old friend. Sometimes, she bears an old grudge; it may or may not be based in solid fact, but she believes it to be right, and will pursue it.
In stories that involve reincarnation, she may have known the character in a past life and met them again in her present life. This clearly causes conflict.
Other times, a canon character killed someone close to her, like her lover, and she wants revenge.
3. She can be a transfer student to a school, or a new employee from another place.
America, Canada, and Britain seem to give birth to the most of this type of Sues; they arrive in Japan and automatically blend in with the others, adapting well to their new environment. Or, in the case of other fandoms (e.g., Harry Potter, X-Men) they come from America, Canada, Australia, Russia, or Japan and blend with the British or Americans.
4. Finally, she can appear out of nowhere.
Usually in these cases, she is treated as though she has always been a part of the canon universe, and is already friends with the canon characters.
Optionally, she fills in another character's role, or is added into the plot of an existing episode/book/volume/movie as if she belongs to the canon group or team.
Notes on personality:
1. She is coldhearted, sarcastic, and even cruel.
She bitches out main characters - even those whom the author likes, but especially those whom the author does not - and occasionally even physically harms them.
Of course, she is reformed, and though she may never become open and loving, she is no longer hateful to everyone around her.
2. She is bubbly and outgoing. In fact, she is perpetually happy.
Her happiness can be used to hide a dark past, which she does not want to talk about or reveal, but will end up doing so anyway.
3. She can be completely emotionless and uncaring.
She hides her emotions because of a traumatic past, usually somehow important to the story's plot.
After meeting one of the canon characters, she reforms and is able to reveal her feelings. Often this follows her falling in love.
4. One minute she is happy and kind, the next she is a heartless warrior. As in, she has what seem to be split personalities.
No one suspects that she can be violent, and she shocks everyone when she attacks someone. This may cause angst if they stop trusting her.
5. She is depressed and always mourning about something.
A canon character (probably one the author likes) falls in love with her despite this.
6. Finally, she can be the kindest, most cheerful, gentlest person of all.
She never gives in or breaks down. She maintains her kindness despite any cruelty that may be done to her.
Notes on abilities:
1. Often, she has some kind of supernatural powers.
This includes telepathy, telekinesis, empathy, and other psychic abilities.
She may have intense ki - or chakra - skills.
She has an unusual mutation or genetic ability, such as wandless magic (in Harry Potter), the abovementioned psychic abilities, manipulation of natural phenomena like the weather or geothermal activity, or control over a particular element (e.g., fire, water, ice, electricity, and so on).
2. She is amazingly intelligent.
3. She has incredible speed, no matter what kind of clothes or accessories would realistically slow her down.
4. She has great physical strength. However, none of this shows physically; her muscles are not large or defined enough to be unattractive or "unfeminine."
5. Her skills and powers are all greater than that of the canon characters.
She is especially stronger than any characters that the author dislikes.
6. She can defeat any enemy.
7. She has healing abilities. This can be either through medical knowledge, or - more commonly - through some kind of mental/supernatural strength.
Notes on story plot:
1. The world is threatened, and she is the only one capable of saving it.
In this case, canon characters' abilities are shunted to the side and considered ineffective (at the very least) compared to hers.
Also in this case, she may be "forced" to work in tandem with her love interest, as their powers combined will surely defeat the bad guys.
2. She falls in love with one of the canon characters through some means, usually unrealistically quickly.
The plot of the story can then revolve around her "melting (insert canon character here)'s cold heart" or "teaching (canon character) how to love."
3. The story can have very little plot. Out of nowhere, Mary Sue appears as a member of the cast. This is never explained.
Often, the author makes it seem like Mary Sue has "always been there."
4. She is introduced as a family member of a canon character. This gives her access to whatever plot that character may be involved in.