Hey I was looking through the first post and I found this:

[quote=Vicier]
Peter Thorn ~ Son of Hermes.
[/quote]

Peter has ice powers, he's the son of Boreas, the North Wind. He's in the Hermes cabin because there aren't any others that personify ice. Except maybe the Hades Cabin but it has already been established that he didn't know Erin or Adam till they met in the kitchens so that's out.