You know, I just had a thought. We still have no proof that Ashura's evil. Everyone just assumes it., because Fai shut him up in the coffin.
What if he did that to save Ashura's life, and that's why he's running? Because Ashura will follow him because he loves him, and Fai's scared that he'll hurt the king? It sounds far fetched, I know, but it was just a random thought.