Origin

As a child, Rex was born into a poor family. Relief came eventually in the form of a government agent. The man offered his family a life of luxury in exchange for Rex. The deal was made and Rex was taken. Rex was made into a soldier. he was trained in gymnastics and fighting and was put through experiments to alter his body including giving him increased strength and the ability to charge inorganic materials. He was used as an agent and was sent to places as a terrorists of sorts. All seemed fine until one day he decided to escape. It might have been a longing to meet his true family and that's exactly what he did as soon as he was clear. He found his family prosperous with young girls. This devastated him and he became secluded. Eventually he met up with Robot and formed the Teen Team.

An Invincible Ally

Rex-Splode was one of the first heroes Invincible met along with the rest of the Teen Team during a fight with the Mauler Twins. Invincible thought he was a jerk and had a hard time getting along with him especially because they both had feelings for teammate, Atom Eve, whom Rex was with. Their relationship was short lived however when Eve found Rex with fellow teammate Dupli-Kate. This angered Invincible, but eventually they became friends

When the original Guardians of the Globe were killed, Rex decided to try to get into the team. When he was at the member drive he got in a fight with future teammate Monster Girl because of her appearance. With Robot as team leader Rex was granted membership as long as he behaves. He coasted with the team and enjoyed his relationship until one day he came into HQ and found Dupli-Kate with The Immortal much in the same way Eve found her and Rex. During one of the team meetings Cecil revealed the real Robot, a young boy who looked remarkably similar to Rex. Robot explained that his body was not sufficient so he made a younger clone of Rex as a replacement body.

During the Sequid's attack on Earth, Rex, Shrinking Ray, and Kate were all benched because they could be used as hosts for the Sequids. However, during the rest of the team's time in space the Lizard League attacked a nuclear missile base. The remaining team went to confront the league and appeared to have the upper hand by killing Salamander and Iguana, but the strongest member, Komodo Dragon, turned the table by killing Shrinking Ray and apperentally Dupli-Kate and all her clones. Rex sacrificed his hand to put an explosive in his head, killing him. Rex thought he won until King Lizard pulled a gun on him. Rex fought it out and ended up getting shot in the head. Luckily King Lizard passed out when he did and Brit showed up to take them away. Rex was able to heal and got a robotic, replacement hand that shot explosive projectiles.

Alternate Realities

During Invincible's fight with Angstrom Levy, he met a group of possible future Guardians of the Globe who had searched for him for fifteen years. This team's Robot turned out to be Rex wearing a suit much like the one the Robot clone wore during the Sequid battle.