Mary Sue: a (female) character who is over-idealized, lacking any real flaws or depth, and usually exists for the purposes of the author's wish fulfillement. Typical characteristics involve having a horribly tragic past, having a lot of guys after her, unprecedented skills or powers, being the "chosen one," and not being like the other girls.
I first heard of Mary Sues when I was a teenager, dabbling in the roleplay forum on Gaia Online (don't judge, I was young and Gaia didn't suck balls yet). There was some post defining the Mary Sue character, with a plea to, you know, not use her in a roleplay. And that makes sense; I mean, you can use her all you want in, say, a romance RP, but an action/adventure RP can't really get anywhere when every female character is a special friggin' snowflake who always has whatever character traits are necessary for the situation.
Now, the hatred of Mary Sue characters seems especially aimed at female characters in fiction (Bella Swan in Twilight) and fan-fiction who embody those traits. At first I felt like it made sense to hate, or at least be very annoyed by, those types of characters. It seemed like the feminist thing to do, hate poorly developed female characters who are too perfect, and to express annoyance at how idealized these women are. Seemingly flawless women, be them in fiction or in print advertisements, aren't really helpful to the cause. But then I started to realize that these "annoying" wish fulfillment characters bear a striking resemblance to male superheroes and fantasy/sci-fi characters. Then I found
an essay last night that confirmed that suspicion:
So, there’s this girl. She’s tragically orphaned and richer than anyone on the planet. Every guy she meets falls in love with her, but in between torrid romances she rejects them all because she dedicated to what is Pure and Good. She has genius level intellect, Olympic-athelete level athletic ability and incredible good looks. She is consumed by terrible angst, but this only makes guys want her more. She has no superhuman abilities, yet she is more competent than her superhuman friends and defeats superhumans with ease. She has unshakably loyal friends and allies, despite the fact she treats them pretty badly. They fear and respect her, and defer to her orders. Everyone is obsessed with her, even her enemies are attracted to her. She can plan ahead for anything and she’s generally right with any conclusion she makes. People who defy her are inevitably wrong.
God, what a Mary Sue.
I just described Batman.
I knew it!
The essay goes on to justify these self-insert, wish-fulfillment power fantasies because men have gotten away with them for decades. Who has rolled their eyes at Spider-Man for being "too perfect"? Well, some guys I guess, but most people don't criticize a guy's fantasy of going from a dorky every-man to a powerful hero who saves the day and wins the affection of whatever girl he wants.
So what IS wrong with young women writing these fantasies? That's what fan fiction is, it's fantasy! Sometimes you're putting yourself in the story, something young people have done for decades but didn't have a platform to share those self-inserts until maybe ten years ago. I should know, I did it all the time, be it in person (those make-believe games us kids used to play) or by using various toys. I'm sure most people my age did it too. Other times you're fantasizing about two (usually male) characters getting together. So they're not well written or interesting, honestly a lot of fan fiction isn't. And it's not like the presence of a Mary Sue is the only thing to make a fan fiction bad.
The critique of Mary Sues especially in works of fiction is another example of the heightened scrutiny women in fiction are often subject to. People are more likely to hate on female characters for being bitchy, slutty, weak, annoying, too perfect or too flawed. Male characters do sometimes get flack for being jerks, but it does seem like the outright hatred is mostly directed at female characters. You're more likely to hear "ugh, I HATE her!" than "ugh, I HATE him!"
Although maybe it doesn't help that female characters, especially in anime or comic books, are written to be weak, annoying, and/or crazy.
Another problem with this critique is that it can stifle creativity. Authors are afraid to create another Mary Sue, and there's a huge chance that the character will be called a Mary Sue for whatever reason. It discourages authors from writing about female characters, which is getting in the way of there being female characters. Perhaps there aren't many female superheroes for this very reason.
What the essay doesn't touch on are the "special snowflake," "not like the other girls," girl-hating Mary Sues out there. These I do have a problem with, because they illustrate the internalized misogyny in their authors. It's generally not a good thing when a girl, real or fictional, claims to not be like the "other girls" - "other girls" being those stupid bimbo cheerleaders, those "skanks" who wear makeup and mini skirts, those "anorexic" girls who are thinner than the protagonist, the catty popular girls, the girls who are physically or emotionally frail, or whatever girl the protagonist's love interest has a crush on. These characters exist in young adult novels and movies as well to be sure, and these sort of characters who are special and different and hate the "normal" girls are harmful because the reinforce the idea that women are, by default, shallow, emotional, catty, stupid, and a range of other negative traits. I know young women who refuse to befriend other girls, or they do but they don't hang out with only girls, they tend to hang out with their guy friends or mixed gender groups, because girls are considered a pain in the ass. Girls are conditioned since middle school to hate members of their own gender. The special snowflake Mary Sue demonstrates this attitude in fan fiction, and her prevalence encourages the problem.
The way female characters are written in fiction and fan fiction can demonstrate deeply internalized misogyny of authors, and the way the nerd community is so quick to hate female characters and label them Mary Sues only shows sexism internalized misogyny in fandoms and the fan fiction community.