So my theory is, on this earthly plane say we have a good hearted man who ends up committing murder, he's not perfect by anything stretch, he just had a bad moment of judgement and killed someone. He suffers from mental anguish throughout his life and spends the majority of his live in jail. Let's say he begins a sort of spiritual quest of healing, healing his heart soul and mind. He makes peace with himself and the victim he's genuinely a changed man through whatever methods got him there. This man passes on to the next realm. I believe the inner work he did on earth has turned him to a healer and he will be assigned a person to help who can't get out of their hellish NDE. Maybe he won't be assigned, and assign himself, thus making him somewhat of an angelic force, with a dark past that he mastered on earth.