I mean, other than trying to kill each other.
If the other side didnt exist, just what would they spend their time doing in their daily life?
They dont eat.
They dont sleep.
I actually wonder about this.
NOTE: Inarius and a few rogue demons decided to join up and make sanctuary so they could get away from the fighting.
Obviously they seem to mutually understand love or -"something like it" and need form companionship.
MAYBE Tyraels book upcoming in october will shed some light on what his life was like in The High Heavens.