Source: comicvine.gamespot.com

Chapter Six: Tyrant Defeats Thanos (In Theory)

After his epiphany, Thanos became a good guy for a while, palling around with Warlock and the Infinity Watch, and defeating a number of threats to the universe.

But we need to talk about Tyrant and his whole deal first. Tyrant was Galactus's robot son. Yes, I know. Essentially, Galactus was bored and lonely one day, so he built a robot to be his friend/son. Unfortunately, while Galactus only eats planets to survive, Tyrant was…well, a tyrant. He conquered and reigned and did evil all over the galaxy.

Galactus eventually had enough and defeated his robot son, then stripped him of most of his power and banished him. Tyrant then returned and tried to conquer the universe again. But Thanos and several former associates of Galactus got involved and stopped him.

Thanos went up against Tyrant one-on-one for a time before making his escape. When asked if he was, you know, going to help out further, Thanos said, "Naw, I'm good. Plus, I thought about it, and Tyrant would have murdered me if I tried."

Lesson Thanos Actually Learned This Time: Pick your battles.