@liztai Good actors are chameleons without seeming insincere. Cheng Yi is good at making his roles multi-layered. You have seen him as the Asura king, right?
I think they had planned for someone else to play the Asura king, father of Cheng Yi's main role, but he didn't work out. So Cheng Yi played both roles and even voiced this one himself. The deeper voice is close to his actual voice, which you can hear when he sings.