Some players want to bring in PC’s whose personality and or build make no sense in a cooperative team setup (or at least not for that specific campaign/group).
One player brought in a PC that was apathetic. He didn’t care about or want to participate in anything. He expected the rest of the party to constantly cajole and convince him all the time about everything. Then he was irritated when we got tired of it and would just say what we were doing. If he didn’t follow, we’d just leave him behind.
Another had a PC that was “ruled by the Lords of Chance” in all his actions. He constantly rolled a dice to see what his character would do even if it ended up being disastrous to the rest of the group.
If we were really playing in-character we would have kicked both of those guys out of the team. You couldn’t count on them and they were more trouble than help. But if we said anything about it they got all offended since “I’m just role playing his personality!”
“Yeah and I’m role playing my PC’s personality which is not to put up with that bull carp any longer.”
I was actually the PC that got kicked out of the party. I was playing a magic resistant Barbarian who was not allowed to willfully resist a save against magic. And all the saves I made were against my party, including one time when the party was trying to rescue me with a teleport, and i resisted staying right where i was, in harms way (this was the first time that they actually knew something had happened and i'd resisted the spell). Between that and his lack of tactics he was kicked out of the group, and put to work somewhere else in the larger group that the party was working with (thus becoming an NPC).
The dynamic of how the characters played off each other and handled the situation made for great roleplaying (and fun memories).