"No," Remus said, leaning his head on a hand. "I don't think Peter is capable of it on his own. He was eager, yes, but not the most skilled. He rarely came up with things on his own. The fact that he's an animagus with such a small form is going to make things more difficult. He has the advantage of being able to almost disappear."
He summoned a tin of chocolate biscuits from the kitchen and popped it open, offering one to Tonks and taking one for himself.
"As for why he'd do it, I can't say. Revenge, obviously, but why now and why just James? I don't think Peter did this of his own accord...I think someone would have to ask him. That's why I suspect there is a bigger picture behind it all."