Dumbledore's riddle about saving Pettigew's life

'But - I stopped Sirius and Professor Lupin killing Pettigrew! That makes it my fault, if Voldemort comes back!'
'It does not,' said Dumbledore quietly. 'Hasn't your experience with the Time-Turner taught you anything, Harry? The consequences of our actions are always so complicated, so diverse, that predicting the future is a very difficult business indeed... Professor Trelawney, bless her, is living proof of that. You did a very noble thing, in saving Pettirgew's life.'
'But if he helps Voldemort back to power -!'
'Pettigrew owes his life to you. You have sent Voldemort a deputy who is in your debt. When one wizard saves another wizard's life, it creates a certain bond between them... and I'm much mistaken if Voldemort wants his servant in the debt of Harry Potter.'
'I don't want a bond with Pettigrew!' said Harry. 'He betrayed my parents!'
'This is magic at its deepest, its most impenetrable, Harry. But trust me... the time may come when you will be very glad you saved Pettigrew's life.'
Harry couldn't imagine when that would be. Dumbledore looked as though he knew what Harry was thinking.

OWL POST AGAIN - Pg 453