Who is Johnnie-O from Everlost and what is their importance?

Johnnie-O is the boy who attacks Allie and Nick when they meet for the first time near the Rockland County sign. He accompanies Allie to the warehouse in the hope of finding food, as well as to help Allie rescue Nick and Leif. When Allie leaves on her quest to find The McGill, Johnnie-O asks for her name, saying he'll need to know it when he's telling people about the girl who went to fight The McGill.