Is it impossible to imagine a fire genasi that's grown tired of being a burden to society/his surroundings and being shunned due to his heritage that he spends his time attempting to master self and damage control, by trying to adhere to laws of society, learning the ways of the monks while intensely studying abjuration magic?
The yearning to learn the arcane ways to protect himself and others from himself should his temper get the best of him. This combined with monk lessons in self mastery, control and discipline in order to maintain composure to the best of his abilities. A LN wiz/monk/rog that has a tendency to snap at, or insult people when he loses himself. Not tourettes, but something milder perhaps. A 6 charisma has to mean something.
Would that fly you think? Of course I wouldn't spew out curse words left and right, but do things in moderation and being reasonable about it.