I make characters incompatible with the general jerkiness of characters made by my group - My current character is a Chaotic Good Bard 4/Swashbuckler 5 who believes in personal freedom and Doing The Right Thing, To The Nine Hells With Whatever Laws Get Broken In The Process. He's merciful, compassionate and kind.
The rest of the party is an amoral TN Battle Sorceror who might drop, a NG Dwarf Fighter played by the guy who doesn't RP and is thus not at all a help to my character's moral standpoints. We originally had a CE Rogue who was pretending to not be CE, though my character suspected. His player retired him because he 'didn't get along well with others' in favour of bringing in a LN Marshal that ignores every single bit of advice on playing a leader type the PHBII gave for the class. >_>;
So now I get to be the jerk because my character, due to his Chaotic alignment and a simple 'Uh, I've been with this group since the beginning, you've been here five minutes, exactly WHO put you in charge?' philosophy, is obviously not at all going to play along with Mr. I Own This Group Now. My character's already been attacked by the guy, so it's not going to go well. But, character wouldn't back down and play nice, neither am I. It's funny, he got along with the guy he suspected of being CE better than the guy who's not evil. But there was a shared alignment factor in the previous guy, I suppose. (My character spent several years living on the Outer Planes, so alignment is actually a meaningful concept to him in-game.)
I also don't always know exactly what I should do, since I'm tied for player who's been doing it the least long(But the other guy has a powergamer mentality and thus optimizes, he's the one that doesn't RP. I just make characters and take what they would take and mechanical perfection be damned). Doesn't help that nobody in the group is usually willing to offer advice even when I ask directly because apparently this would be some horrible sin, so I end up doing something stupid sometimes and getting yelled at for it, or just simply sitting there not knowing which course of action I should take and which would just plain be doomed from the start and trying to think as fast as possible. <_>
I'm doormat-y sometimes because I've been doing it the least long and have developed a 'well we're not going to do what I suggest anyway so why even bother pushing for it' mentality. So I don't speak up and insist on something often enough, both in and out of character. I've gotten better in-character, but ooc ugh.
Since I don't optimize and don't push I end up too often not being all that useful next to the powergamers, which just frustrates both of us since I end up being the weakest member of the group in terms of what I can do.
I resent the things that annoy me too much. I'm annoyed that the Marshal attacked my character, even if the damage was non-lethal and inspired by my character calling him a coward, to the point of pondering my character's ability to take the other character in a fight or if it would be better to wait until he trances and CDG him. I won't of course, I'll just retire my character once we're out of the current dungeon if he doesn't improve, but my character can't work with this guy without it ending badly, as already demonstrated by the attack, which came with an insult and a threat to have it not be with the flat of the blade next time. And I'm letting myself get resentful over this because he's entitled to his character too, even if the most IC thing for me to do would be to just have my character leave. Except I like my character and don't want to retire him. So metagaming, which I hate, and resentment.
Which brings me to my problem of not being able to think of reasons for my character to stay with people that annoy him rather than go off on his own merry little way. I had the same problem in a previous campaign after a character was introduced by way of poisoning my character(The Fortitude Save against said poison that came up a Nat20 was the best 'Oh yeah? Well eat this' die roll EVER) and I had to metagame to hell and back why exactly my character was staying with someone who had tried to poison him. <_>
I'm also too attached to my characters. <_> And I slow things down by wanting to RP stuff and have our characters talk and want to develop them. I want to develop my own character and I honestly want to know about the other characters as well. (Especially since, you know, if we actually KNEW each other I'd have an easier time with why my character stays with an obviously hostile other character.) So when everyone's all 'let's fast-forward to the dungeon' I'm the sole 'let's RP a bit on the way' vote, and end up trying to strike up conversations in the dungeon.
So yeah. I make annoying characters who stick too hard to their morals and I don't know/abuse the game enough to keep up and want to RP too much in a group that doesn't want to RP. I'm the problem player who's always clashing against the other players. ._.;
(I'm also guilty of the 'My background is half a page long, and that's the condensed version that glosses over stuff' thing, and my motivations aren't for physical stuff but for things that aren't likely to get touched on at all, and I let that annoy me too.)