This is about the anime character. For the monster itself, see Centaur.
Centaur is a powerful warrior who starts out fighting against the Searchers, but eventually allies himself with them.
Centaur lives in the ruins of Alta Vista on the plains, along with his friends, Celious and Dragoon. They guard the Fountain of Warriors, but when Gray Wolf defeats he and his companions in a battle, Centaur believes that, out of honor, he must follow Gray Wolf's commands. He tries to capture Genki and the Searchers for Gray Wolf, but gives them a fighting chance to escape, knowing that what he is doing is wrong.
Each Centaur challenges a member of the Searchers to a fight, using old coliseum fighting techniques. Centaur fights against Genki, but their fight is interrupted by the Salamander Troops. They burst into the coliseum to try to capture the Searchers themselves, injuring Centaur in the process. That seems to be the straw that breaks the camel's back, and Centaur finally decides that working for the Baddies is too dishonorable for him.