negative Traits in game play

I have an evil, outgoing sim married to an insane, family oriented sim. Their romance bar is usually high but their friendship bar hovers somewhere in the middle; it's as if they love but are wary of each other because they never know which one is going to go off, hehe. The evil one is has the fabulously wealthy aspiration and is in the investor track of the business career; he also inherited the family home and has this picture perfect family thing going. But he has a brother who basically dropped out to become a street musician, so when they're together they're always arguing about careers or family and so on. It's pretty hilarious. I decided to have the daughter of the evil one run up as many negative character traits as possible so their relationship is volatile, to say the least.