Responses
I think he's lying in wait for Yuyang in the locker room. He is roommates/friends with the redheaded guy that was taunting Yuyang earlier and the author made it pretty clear that the purple guy is planning something when the author showed the purple guy giving an "okay" sign after talking to Yuyang. Yuyang also talks about how to thinks the purple guy is "greasy" and says he doesn't like him.
Yuyang has a crush on the main character from the author's other work - Guang Xiang. If you read that, Yuyang shows up and confesses to the main character but is turned down.
Ok, here is what is going to happen:
Yuyang is going to get hit on by the purple dude in the bathroom (which is obviously a trap for something) and Lihuan is either going to walk in and save him or get the wrong idea and leave hurt.