i have played several campaigns in 4th edition and one in pathfinder (an adaptation of 3.5)
i usually play a high wisdom, medium intelligence and low charisma character (druids, avengers, rogues, that kind of tea), so that i dont have to be the face, but more the eyes and ears of the group.
somewhere during the 3rd campaign, i realised i always roleplay autistic characters as well; usually quiet and reserved, making thought-out desisions (except for that one cleptomanic rogue, but buy was he fun), although i they usually stood their ground if needed.
in one campaign, i played an avenger, and one of my groupfriends was an AoE wizard that liked to blast the area i was in (i was surrounded by enemies usually, due to my build; if i get hit i do more damage).
however, he was unlucky with the dice in that he usually only hit 1 of the 4 or 5 enemies in the blast, for low damage, but did a critical on me.
in-character, it looked as if it was deliberate, and got nearly killed twice due to that; i then warned him (in character) that it was the last time i'd forgive him.
now of course, it happened a third time that he threw a fireball at the group i was in (while having other targets), so i got angry and unleashed all the power i could in a single turn (a movement action attack, minor action attack, daily attack and another daily from an action point; the movement also got me hit on provoced attacks, triggering my bonus damage a few times)); i think i did about 200 damage in him in that single turn (he had 60 hitpoints at a maximum, so the biggest part we found of him was one of his thumbs)