Fan Casting Splinter in Teenage Mutant Ninja Turtles: Heroes In A Half Shell

Splinter was the pet rat of Hamato Yoshi, for years he mimicked the movement of his owner when he was training in the art of ninjitsu. But years after Yoshi left the foot, he went to America, later on being killed by the foot. Then Splinter and four baby turtles were mutated and he became their surrogate father. Training them in the art of ninjitsu so they can defeat the Foot Clan.