Some TMNT stuff really isn't for little kids.
Baltizar (Balt for short) is a former warrior slave abducted by the Dimensional Council to fight in their gladiatorial games. He claims to be from a race of natural warriors, living on the side of a volcano and fighting each other as well as dangerous animals. At some point prior to the Turtles' arrival, he met and fell in love with Renet.
When the Turtles were brought to the slave cells, they were placed with Baltizar. He informed them about the Dimensional Council and their games, urged them to select weapons for their first match, and fought alongside them in the arena. Initially assuming that the Turtles were less skilled at combat than he was, he discovered that they were warriors in their own right. He assured them that they could be "pretty good" at fighting if they spent a few years training on his world.
That night, Rangor spoke to him about the possibility of a slave revolt, but Baltizar—assuming he would be the natural choice—did not think that he had the smarts necessary to lead. He was then electrocuted by one of the guards in order to guarantee his loss in the arena that morning, as the shock left him barely able to stand. The Turtles defended him from the horde of new warriors pitted against them, and Baltizar soon recovered enough to join the fight.
After the battle, he bid farewell to the Turtles, and accompanied Renet on a time-traveling date.