heh. i only played for a short time with 3.5. i tried to be a smiling, pleasant, sociopathic mage. the dm let me. i liked to brew tea from things that should not be drunk, collected hands and, when i ran out of spells in a pretty desperate fight, threw my string necklace of drow hands at the line of drow warriors and tangled one up so he fell over.
i also tried to sacrifice prisoners to vecna. the cleric had such a low intelligence modifier that whenever he caught me doing this sort of thing i was able to talk him out of attacking me. the player behind that character got incredibly angry. seriously, dicerolls in that context are like jedi mind tricks. all i had to do was convince his character i was up to something innocent and the DM would not allow him to do anything about it.
.........
years later, as the only player out of my friends who had played the game, ive been roped into running the 4th edition module keep on the shadowfell that comes free from the wizards website. its been a lot of fun, but i have so much respect for the dm who let me get away with that crazyness all those years ago. its so painful stopping a group from pulling the gaming session apart. ive got a particularly annoying rogue player who thinks the other players wont mind me roleplaying him robbing all the houses in town for a real life hour while they look on, and gets angry when i wont let him do that.
also the dwarf player in our group is awesome. hes turned the goblin prisoner, you can befriend in the module into a sortof pet/sidekick. he smuggles him into town past the xenophobic guards by hiding the goblin in his backpack and uses him to cheat at cards.
one annoying player can cost the game so much though. ive invented the npc of big maude the pig farmer, an enormous drunken hairy women with a halfling fetish, who appears whenever that damned halfling rogue tries to talk whatever female npc hes near into sleeping with him. he just wont accept "no, im not roleplaying your violent antisocial erotic fantasies". also the wizard has to keep a sleep spell ready to knock him out whenever he tries to do something like attack and rob a random stranger or throw rocks through the mayors windows. extremely evil chaotic characters just dont work unless everyone else is playing along as well.
my sister got roped into a session a while back. she ran with an elf avanger, which in 4e is like a holy monk dressed in big billowing black robes who runs around dealing death with a greatsword. with her pregenned character stats and a magic frost sword she could roll a 4 and still hit. she also chose to serve the raven queen, goddess of death. whenever the party got what they wanted from a captured foe, she would ask the prisoner, "do you accept the raven queen's blessing?" if the prisoner said yes, she would execute them.
if i was a player i would probably most want an eladrin dual weapon fighter. the dual weapon warrior builds in 4e are pretty freaking fantastic, and with the eladrin 5 square encounter teleport, a lot of combat encounters would be very fun. you would be able to clean up minions even faster then a mage with fireball and laugh at a lot of the traps that try and fix you in place. also he could use double swords later on, once he got the feat for them. character personality would depend on the group and the dm, but if anyone acted like the "can i roll for rape?" rogue character i describe above i would probably try and kill them.