"Oh." Peter hesitated. No wonder he hadn't recognised the man - his own age or younger, taller than him with auburn hair and a friendly, almost rougish smile. Looking closer, though, he realised the eyes should have given it away. There was no mistaking the knowing intelligence in those twinkling blue eyes, even without the long grey beard or lines of age. He looked practically angelic.
For a moment Peter simply stared, then he gave himself a little shake. At least this Dumbledore definitely would not remember him or any of his more terrible misdeeds. "Peter," he said coming back to himself. He hesitated a moment more before reaching out to shake the offered hand with his left. It was very awkward, and ended up being more of a brief clasp than a handshake. He was very self concious of the stump of his right wrist, quite visible, and kept it tucked tight by his side for what little good that did.