Steroid addiction.

Haha! Yay for half-a-decade-old callbacks

Anyway, let's make up some fun theories about the party's dark secrets we never find out. This is not Persona, we don't really get to spend a year getting to know the characters intimately from every angle, but there must be done stuff they just won't admit to others! Apart from Sabin's steroid abuse, I'd say Edgar is secretly a crossdresser, while Terra secretly writes yaoi fan fiction about those two.