He used to be the most evil of everyone in the land, but then he got sent to prison, where he was abused by the prison warden Sam and tortured by Quackity. He keeps the trauma with him even after he was able to escape with Technoblade (R.I.P.) at his side. The reason for his villainy is that he misses the simple life, when it was just him and his best friends, Sapnap and Dream. He will do anything for his friends--including kill his enemies. He's just cold and cruel like that.