The Guardian Demon

Tommy's father, Nick, had never been an angel. He took care of Tommy by himself, since there were no other close relatives, not since the accident that killed Tommy's mother and left the child wheelchair bound. Years later, when Nick passed away after a short, terrible illness, Tommy was left alone. Well, not completely alone. They say that we all have a guardian angel, and a demon trying to tempt us.
But what would happen if one didn't have a guardian angel? How can one put up a fight against temptation without the angel's help? And more importantly, how deeply can one succumb to the demon's whispers?