Huo Xudong

He was the disciple one of the 7 villains of Bloodsin City. (It was the monk). Hu Xudong came to Bloodsin City to train, he caught the attention of the monk and was forced to be his disciple. He was poisoned just like Xiang Shaoyun. Since they had the same thing happen to them, they quickly became good friends. But who would have known, after coming into the Devil Realm, Xiang Shaoyun revealed his amazing powers and Hu Xudong betrayed Xiang Shaoyun to get his forbidden martial technique. Shaoyun was furious and vowed to kill him. As for what happened next, IDK, I haven't gotten to that part yet :)

Update: He was actually an assassin from the Rat Assassin Organization.