Roddy carries a good luck charm given to him by his parents.
Roddy had huge black framed eyeglasses, and has white/blond hair (that's cut short), he also had very pale blue eyes. When Roddy is at 95% snake completion he is mentioned to flick his long forked tongue but is still mostly human. When Roddy is finally transformed into a snake, he comes out as a long yellow belly king snake, which helps him later in the book.
Roddy has a "wimpy" personality, mostly because of his big fear of snakes. Also, this may be because one of the kids at school told him a legend of the camp named Serpo (a giant snake that supposedly lives at the bottom of the camp's lake). When he is in snake form, Roddy is aggressive toward the other snakes at the laboratory, ultimately dodging an attack from Dr. Crawler, causing Dr. Crawler to inject himself with venom.