Prior to the Great Change, Leg Horse was known as Prince Horace, co-ruler of Space Funeral with his brother, Dag. After the Great Change, he was transformed into his current corrupted form.
Leg Horse is first seen fending off Blood Wolves in the wastes. He demands Phillip either "join him or die" then take him to the Blood Cavern to see Wizard Grum, saying "the fate of the world depends on it".
After finding Wizard Grum, he talks with the wizard alone. Phillip also speaks with Wizard Grum, who tells Philip that his journey lies north in the City of Forms. Having his own reasons, Leg Horse joins Philip as a party member on their way to the city.
Leg Horse finds his old castle in the Ghost Forest. 20th Century Boy appears and insults him, which prompts Leg Horse to attack. After his defeat the boy reveals himself as the corrupted form of Dag, who lost his mind protecting the house awaiting his brother's return.
Leg Horse and Phillip go through the Northern Wastes to the City of Forms where they find the corrupted heart of the kingdom. The party encounters Moon and defeats her in order to return Space Funeral back to its former state.
In Space Funeral 2, Leg Horse and Phillip stop the new artists continuing Moon's work. In Space Funeral 3, they are summoned to the scientific land of Earth Birth, where they must find a way back home.
He seems to know Aquaman, as before fighting him, he shouts "YOU!"