Kaz Heater is The Demon's son. He was the one who stole the god's soul, thus turning him into a demon.
Kaz Heater is one of the main antagonists of the series. He is a massive manipulator, impersonator, and liar. He is the heir to the dark throne of The Demon and has set out to make Team Demon Light's lives torture.
Kaz Heater is the son of The Demon, then named Xeren and a demon woman named Xatulia. Xeren was the king of the gods when Kaz was born as it was before his ultimate fall to darkness. Kaz was the oldest of Xeren's children, and as he was half-demon, he had a dark twisted side to him.