Mattis is a wiseacre guy. He always thinks he knows better than the other camp members. He debuted in the early spring of 2010 and is most known for the summer camp 2010. He also screamed high when William called him an "asshole" and also when Tony called him jerk. He complained when Tony and Patrick talked to each other in the bedroom next to his bedroom. He was the main villian of the summer camp since William quit at the camp during the summer camp. Mattis quit the camp after the summer camp 2010 since he needed to move in order to attend a high school. He was mentioned during the summer camp 2012 and has not appeared in anything since he leaved the camp.