Great job! I'm still digesting everything... such a great character study, I felt a lot of empathy for Peter.
A few of my favourite parts:
What if Lucius wasn't flirting with him? What if this was all some sort of giant plot to get him to join You-Know-Who? Peter laughed silently. Even he had to admit that seemed rather far-fetched. There was no reason for You-Know-Who to recruit him. None whatsoever. He was positive that You-Know-Who would be recruiting far more useful agents.
Oh Peter. That's exactly what's happening. :(
"You're shy," Lucius said, his voice silky. There was nothing of the vulnerability in his gaze any more. Instead, Peter felt as though he was a bowl of milk being eyed by a hungry cat. "How old are you, Peter?"
Even though Lucius later denies ever being attracted to Peter, I think it's really believable that he would be attracted to the power he holds over him.
He'd never felt particularly brave but he wanted to be. Oh Merlin, how he wanted to be brave like those two black haired boys on the train.
I loved how the ending brought everything together and answered the question "what was it about Peter that made him a Gryffindor?"
Also, wonderful portrayal of the way fascism would appear tempting to a man like Peter. Just fabulous!