So:
Khorne: Anger issues. Little setbacks or minor irritations make him so angry he puts his fist through the door. Then he's pissed off that he's broken the door to his kitchen
again. So. Fething. Irritating.
Slaanesh: Bi-polar. Definitely has fethloads of fun when the going's good, but when it's not there's a slight tinge of the desperation addicts have when looking for the next hit. Heart and soul of the party, but probably not very enjoyable to be them.
Tzeentch: Neurotic conspiracy nut. You know that one guy who will try and tell you at every opportunity that 911 was staged by the US government? This is that guy. Except somehow he's implicated in it as well, but he has a cunning plan to beat them. Of course he won't tell you, you might be part of it as well.
Nurgle: Hobbyist. Utterly content sitting in his study of a Saturday evening,
painting his little toy soldiers spawning new daemons and concocting diseases. Fantastically pleased when his latest batch of plaguebearers drags down a Wraithknight in their first battle. Tough list he was facing too. Scatbikes and Wraithknights as far as the eye could see. Generally fun guy to be around, if you don't mind the lack of deodorant