Heaven

You've been in heaven for some time as it was just another peaceful day until there was a scream. You went to go see what it was as it was an angel who got killed by one of the demons here in heaven. So you flew as fast as you could and warned the others.

Hell

Satin was planning an attack for heaven as everyone had to participate, once one of them attacked an angel  there started to be a war against angels and demons/dark angels.