@ Purpose: So far the group consists of a fighter, a rogue, and a sorceror, with something cleric-y possibly on the way. So the basic functions are covered.
Mechanically I want a fighting character with some versatility (as in: not useless outside of battle) - for roleplaying purposes I don't want some stern ascetic, but something with more of a charming rogue vibe (without stepping on the actual rogue's turf). Also it's more of a roleplay-focused campaign, so I don't have to be 110% optimized, but of course there's also little fun in a character who can't really do anything.
@ Race: Haven't really decided on one yet. My first thought was human or dwarf, but aasimar or tieflings are also on the table.
@ Irrepressible: Why is it better than Steadfast Personality? With the former I can't make Wisdom a complete dump stat (which doesn't seem like the best idea anyway), but Irrepressible seems more situational. In my experience charm and compulsion effects aren't used THAT often. Though as I said: my experience is limited.