Thaliel had 2 sides to him in life. A good one and a bad one. He couldn’t control them, so when he was good, he was the best person ever. But when he was bad, he was a s*rial k*ller, and was sentenced to de*th. In the end, angels didn’t know what to do with him. So they sent him on a quest to find out what kind of spirit he wanted to be and seeing if he could change other demons’ masks. The drama masks are to show both of his emotions. And I didn’t know about gangle before this, so I’m not copying.
