Oooh, I love that! :) Peter won't like being thought of as a kid, but he'll admire and appreciate her intelligence! :) He's going to be quite confused, too, about all the other Peters running around! ;)
I mean... there's not a whole lot to go on about James. We know that he was a prankster at school, and that he and Severus Snape had a near deadly rivalry. He ended up winning Lily's heart, and producing Harry. Then he was snuffed out in his prime... so I play him as a lovable prankster/jokester, with a heart of gold. In my headcanon, he's a little calmer than Sirius, but definitely not as bookish as Remus. Though, they're all brilliant to become animagi so early and without any official training.
Sorry, I wrote a novel for you. ;) Anyway, James is a good guy. xD