Rex and Shawn once used to be very close to each other intill one day he was hit in the head with a baseball bat by two thugs. He forget who Shawn was. All he knew now was that there was some kid stealing attention from his parents. He worked hard to kill him so he could have his parents back. The reson Shawn has not killed him in battle was because he loved his half brother too much to kill him. But sadly Rex was running after Shawn when he tripped and fell into a batch of toxic waste.