ChaoZu is best friends with Tien. He could comunicate telepathicly with Tien. ChaoZu was a weak fighter but was very strong willed. He sacreficed his own life to try and kill Nappa but he failed and was sent to train with King Kai. That was the second time he died. So it was harder to wish him back. He like Yamcha and Tien fadded out as characters.