The key parts read: "The reason why there are no parents is because they died in a car accident on their way to pick Ruby up from Bunny Scouts. Max was in the car and survived, but suffered from brain injuries, hence the reason why he always messes up in the show and Ruby has to look after him."
But wait! There's more!
"Max is mute because their grandmother molested him at a young age and he is so traumatized that he created Super Bunny as an imaginary hero to somehow save him from his life. He also plays with the ambulance and police cars because he remembers those vehicles were there during the accident."