In my opinion, it's wrong when you don't roleplay a person, but a living gimmick. If you have a mute whose only defining trait is that it can't talk then you will have a very annoying character - without personality your every emote won't have any message behind it but "look I can't talk!".
Actually, gimmicks generally are a bad idea if they create a highly unusual character and if you're unsure you can pull them off. Mutes, blinds, cripples, people haunted by spirits, big children, mentally retarded, crazies - Sturgeon's Law applies fully here. 99% of these concepts will, when roleplayed, turn out to be pure crap. It's better to create a more normal character, and make it unique because of its interesting personality. And interesting doesn't mean something wildly out of scale. That's annoying too.
Another thing that pisses me off is when someone deliberately creates a character just to disagree with other players. Create an anarchist only to sneer at everything your city leaders say, or a vocal pacifist in Magnagora, or an anti-Light Celestian, or anyone who will try to preach to others all the time and you will have my eternal wrath.
Speaking of the last point - preachers are basically a bad idea if you want to preach towards PCs from enemy factions. Other players made a deliberate choice to join the org they're in and not yours, and trying to persuade them that the choice was wrong (even if it's ICly only) tends to piss them off. Which will result in violence most of the time.

If we're in the role of describing character's evolutions, I can do mine easy.

Veyda started out as an ambitious, manipulative young krokani.

Now he's an ambitious, manipulative old faeling.

Presto poof, roleplay.

The rest is top secret.

Mother Night whispers in your mind, "Veyda... you are far too bright and cunning to be a krokani..."

Mother Night whispers in your mind, "... let me aide you..."

Shadows whip and coalesce around your form. You scream out in ecstasy and anguish as your skeletal structure shifts, bones loudly creaking. Pain shoots throughout your body as you feel something tear audibly out of your back.

Mother Night whispers in your mind, "... smaller... but much more appropriate."

---

I donno, sounds nifty to me.

Lets see, Akui is stubborn, occasionally obnoxious, has a temper, and has an argumentive style roughly equivalent to "I'm right, you're wrong, so why are you still talking?" She's also loyal, devoted, and compassionate towards those things and people she does care about.

I guess I feel it is important that, if someone desperately wants to smack the crap out of you, it's for IC reasons. I had more of a point to this post, but then I started yawning and forgot what it was, so when my brain works again, I'll fix it.

Ah, the lesser races, so amusing with their meaningless ambitions. We are warriors, forged in the heat of battle since the ancient times, and that's what we shall always be. Feidhmigh Ar Son Serenguard!

People say it's bad when you put too much of you into your character.

This... is all brand new, though.

To preach to the choir, RP is about evolution and balance. Roleplay is playing a role, being someone who could be real. Try to think of it like this, if you were wandering around in the game and met your character, how would you view him? You don't neccessarily have to like him (I don't really like Kira all that much anymore), but he has to appear to be in charge of himself, instead of a puppet with random strings being pulled by an inept puppetmaster.

Also, don't be too concerned with what others see to begin with. Just because something isn't readily apparent doesn't that mean it isn't there.

Kira began as a friendly, loving character who wanted to help everyone in Celest, but now her view has changed. Sure, she smiles and greets anyone and everyone all the time, just like she's always done, but she is far less happy. Her actions haven't changed, but the satisfaction she gets out of said actions, and the happiness she feels, have both fallen drastically. You wouldn't know this by observing her.

See, you understand after all!

Of course, I shouldn't have expected an inferior faeling to understand, but I will shed some light. Apparently, the lesser races find my behaviour offensive for some reason (perhaps because of their own insecurities, I never bothered to try to understand them), and because I believe that everyone deserves respect, I don't remind them too often of their own inferiority.

...not quite.

At least you took SOMETHING from your Serenguard training .

Thank you, High Chief, you are most kind. I do my best.