Q: "Quirky" characters.

I'm sure we've all had them in our games, or at the very least had That One Player who insists on want to play them -- the PC based entirely around some (often annoying) quirk. The player has come up with some kind of gimmick, or something that they think will make their character "unique" and thus stand out, and is hellbent on pushing that quirky envelope as far as it will go.

Sometimes, the quirkiness can result in a surprisingly well-developed and entertaining character (the gnome barbarian with a tendency to bite the ears of his adversaries who brought the concept of "burnt bean water" (= coffee, of course) into the civilized lands, while certainly weird, was one of the best characters in that campaign) ...

... and sometimes, not so much with the development of any kind, such as the spellcaster whose entire existence boiled down to "has a traveling show based around bigarse tarantula familiar and only really talks about the spider except when player is demanding all attention". (the especially facepalming bit about that character was that the spider got more development than the character did. no lie.)

And of course these are extreme examples in a way, but there's always the garden-variety quirks ... The player who really really really wants to play an Asian-themed character in a European-themed fantasy game; the one who wants to be a were-porcupine in a WoD game. Even little tiny quirks -- constantly emphasizing a single oddity of appearance or behaviour -- can be horribly special snowflake behaviour if it's overdone.

But not all quirky characters are automatically a bad thing. Like the gnome barbarian, it's really all in the play and the presentation: if all there is to the character is the quirk, especially to the point of driving said quirk into the metaphorical ground, that's a character rapidly on the fast track to becoming a misery to have in the group. But if the quirkiness is just one facet, if the character has depth and development beyond just "I'm a [whatever]!" -- and most especially if the player isn't using the quirk to try and dominate the game, then it's all good.