Not sure if this is too far off the prompt, but what if little Matt was a real friend of little Foggy until he died in the accident? Little Foggy couldn't cope with his friend's death, so he started to imagine Matt alive. Matt's father is murdered a few months later, which triggers Foggy even deeper into his hallucination, creating the whole idea of Matt as a lonely orphan. The hallucination is too painful to deal with after awhile, so he tries to block it from his head. He succeeds until the pressure and stress of college causes him to snap, his powers go haywire, and that's when he not only brings his Matt hallucination back but the hallucination starts affecting others...