Consider this: 'There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them. They themselves are equally pleased by both errors, and hail a materialist or a magician with the same delight.' ~C.S.Lewis, The Screwtape Letters
Let's assume humans exist to exercise free will in forming our characters either in openness to Higher Forces or the self-centeredness that leads to rejecting them. As you choose to create a relationship with them (being forgiven by grace rather than through your own goodness) then, in heaven, your life is supposedly different.
Some religious traditions suggest this self-same process applies to angels. However, unlike with humankind, angels have already chosen for or against the staus quo. 'Just like humans, the Angels may undergo a period of probation during which they are free to choose between good and evil. What if spirits who rejecte the ways and universal laws of Higher Forces become demons?