That Little Rascal Beneath Huayue Mountain

Qingyan was on his way to a ruined temple to exorcise a demon when, whoops, he fell for the demon's trap. The thing in the temple was so hard to deal with that he failed to exorcise it and got himself caught instead. What a terrible bargain. Happy ending, sweet story, written for fun. It's part of the same series as the other three short stories. I'll write a full-length novel later. Theme: