If Aerophobos sides in at all, it'll be against Atroxica - he has very firm opinions on tools who can't be controlled and masters who fail to keep their underlings in line. Demon Lords are supposed to bicker and snipe and be rude to each other within limits, but creatures of lesser standing simply do not behave towards their betters in power the way Atroxica's minions think they can get away with.