Alrighty...omfg where to start.

Okay *breathe*

Here we go.

The almighty OC, the central character of the story that makes everyone else useless. The most perfect (typically a girl) person to ever exist.

Am I guilty of this?

Lmao, yupperooni.

Nah, but really, I used to do this and I'm sorry to anyone who's read my old shit where my character was a total Mary Sue.

Haha, now my main character's an unstable, fucked up bitch but it's gucci :'))))

ANYWAY

Let's just actually explain this widespread issue.
The Mary Sue
(heh, that sorta rhymed)

Mary Sue = typical perfect character who's gorgeous and has every desirable trait ever.

A mistake that people starting out on here make is creating a character that is an insanely glorified version of themself. Said character typically includes...
-looks that would give Aphrodite a run for her money
-everyone is attracted to the character and they have no enemies
-they have all the powers in existence
-they take the place of the main character
-and much more

Okay, so with those main points, let's divide them up.

LOOKS

So typically, the character is a girl who has long hair, is petite or the next fucking Kim Kardashian, and had bright eyes that don't exist in real life.

In short, they're made out to be pretty asf and make us feel like rotting potatoes.

They usually don't have many physical flaws and that sucks because I know damn well that we all have insecurities.

Like for example, I personally think I look like a prepubescent ten-year-old still even though I'm 17 now lmao. Or the fact that I get acne around/on my nose and shoulders. Or that my eyes are the color of crap. Or that I thought my braces made me look like I wanna die whenever I smile, but I got them off and now I feel my teeth are too big for my mouth.

But that's just me.

We ALL have insecurities and there's nobody with perfect looks. So please, include flaws and make your characters believable. Your OC is most likely a teenager, so they're gonna be more insecure than ever.

Sure, they can be attractive and have above average looks, but at least make it realistic.

SOCIAL

Lmao there is NOBODY that everyone likes. Your character isn't an exception. Quit making them so damn popular.

Am I guilty of this? Formerly, yes.

At the very least, if you're gonna have your character be well-liked, make some development.

I don't have much else to say about this, I think you get the point.

POWERS

Fuck. Literally so fucking guilty.

Okay, so this isn't specific to every fandom or whatever but I do hp shit and know this is an actual problem.

The OC is a flying elemental monkey and every other animal that's also a werewolf and has telekinesis and mind powers and invisibility and is a mermaid that can change at will all while pooping out rainbows and perfectly singing showtunes.

Okay, I didn't even go that ham on powers but fr I've seen shit pretty damn close to this and I actually wish I were kidding.

So yeah, I'm gonna defend myself here for a bit. Here goes.

If you've read the Anna Black series, you should know that Anna's a sorceress. Cliche? Mhmm, I'm aware. But it's explained later.

There's literally this whole backstory that talks about the powers, how they came to be, how they're destroyed/obtained, ect. Like I made a legit plot out of it. And not only that, but I made it a character FLAW.

Yeah, that's right, her powers are a flaw.

It's not like Anna fixes everything with the flick of a wrist or manipulates Harry to fall in love with her when she feels like it. She lives like a normal person and hides away her ability because she's ashamed and unwanting of it. Her powers are dark and it's a constant battle for her to stay sane and good.

So yes, it's okay if your character's an elemental, can speak to animals, or do wandless magic, just make a purpose for doing so, make a backstory and reason.

BEING THE STAR

Ahaha, stop.

So this is just a gamut of problems. I'll get into a few.

Don't make your character be a line-stealer of other characters. Be original, please. And yes, I know from experience.

Don't make every other character a dull, unlikeable prick to make your OC stand out.

Don't have your character take over the whole story. For example...

In many Harry Potter fanfics, the OC takes over as the Chosen One. It's a very hard thing to balance out when you want to main characters like that (really, I get the struggle and I'm still battling this issue) but don't have your OC take over the original character.

I'll talk more about this specific example later.

WAYS TO MAKE YOUR CHARACTER...DECENT?

-don't make your character perfect! character development is honestly an amazing thing and you should include it.
-your character should have flaws, inside and out
-diversity!
-go against the flow! you can do whatever you want with the story to change it...it's YOUR recreation, so go wild!

Hope this helped?

Comment suggestions pls and thanks.