Caiman was a survivor of Cassandra Nova's wild sentinel attack on Genosha. He later joined a gang of fellow former Genoshans amongst the ruins of Hammer Bay and was led by Angelo Unuscione. Along with his fellow gang members he came into conflict with Professor X over control of the island.
The gang was disbanded post M-Day when most of them lost their powers.
Caiman takes the form of a large humanoid lizard