Frank didn't think swapping bodies with an old man and doing a deal with a demon would cause too much trouble. He just wanted to be taller and see that beautiful angel, Ariella again.
Michelle didn't think that lending her witchcraft book to Frank would lead to a ridiculous journey through Hell, Limbo and Heaven, where she would learn to shape change into a hawk.
But Michelle had a good reason to lend Frank that book and she had an even better reason to follow him anywhere he went.
Even though Frank just thought of Michelle as friend, he didn't realise how important she would be to him and Michelle didn't realise how important Frank was to the rest of the world.
Frank wasn't just a skinny little kid, he was the 7th Saviour!