Mason Heglin is Emmett's nephew. In the episode, "Double Whammy", he and Charlie had a race and Charlie won. Emmett mentioned that Mason sleeps with a rabbit that he caught. He did not say if it is alive or dead. He returned in "Wentz's Weather Girls". They were supposed to have a race with bicycles but Bob wouldn't allow it, so Emmett and PJ raced and PJ won. In Wentz's Weather Girls, Mason had an afro. He is 4 years old, like Charlie.