Responses
Bro really got that turned on from sylhan saying that he's afraid of him, he wants to feel like dominate alpha so badly and wants to make sylhan his little vulnerable omega. Honestly if gjord finds out what that greenhorn did, gjord would actually skin him alive
After rereading on chapter 13, I realized lister did all that because slan told him he "cried" because of lister, lister really likes it when slan gets sad over him, just because of that simple lie lister was being all day nice because he felt good slan being sad over him, he's actually insane. He doesn't like slan's ego so he belittles him everytime just to up himself up and make slan see him as superior.
Sorry Abt my rant, I just find lister to be a very interesting character because I know some people that is like him as well (unfortunately)