As a young man Cul was riding around Aesheim, aka Earth, when he was attacked by a giant and thrown off a mountain. Breaking both his legs, Cul bandaged himself up and crawled to the giant’s camp to enact his revenge. He drank the blood of all the giants, save one, whom he wrote a chilling message in blood: “Gods do not live in the sky. We live on the Earth. And you do so at our pleasure." The terrified giant spread this message far and wide causing Cul’s reputation as the god of fear to spread across the Earth.
As the eldest of Bor Burison sons including Odin, Vili and Ve, Cul was first in line for the throne when Bor died. For centuries Cul ruled Aesheim until his brother Odin received a vision from Yggdrasil, the world tree, warning him of all the future harm Cul would do to Midgard’s people. Teaming up with his other brothers Vili and Ve, Odin confronted Cul at his citadel but is unwilling to kill his brother. Odin instead traps him underneath the ocean leaving him to rot. Cul feeds on the fear of humans to survive and stews underneath the ocean, waiting for his time to strike. With Odin dead and Asgard destroyed after the events of Thor: Ragnarök, Earth is prime for the picking. The Blip has introduced a level of panic and fear on Earth that can empower Cul to break out of his prison and enact his vengeance again his brother’s precious Midgard.