Rex is the son of protagonist Michael Britten and his wife Hannah Britten. When the family is involved in a car crash, Michael's life splits into two realities. In one reality, the "Red Reality", Hannah survives the accident, but the couple must deal with the loss of Rex. In the "Green Reality", Hannah dies, and Rex must deal with the loss of his mother. Rex's favourite colour is green. His girlfriend is a girl named Emma. It is revealed in the episode "Game Day" that in the Green Reality Rex got his girlfriend Emma pregnant right before the accident. She broke up with him. But later told him about the pregnancy and that she had miscarried. Michael discovers that she is still pregnant in the red reality.