why honey bit his head?

I believe at the end, that strange person said about a mark disappearing. I think honey removed that mark by biting on his head as a favour. Suggesting whatever was with the mark wasn't good

I think that person was talking about the dangerous person from the shrine. I have a feeling that honey went after the dangerous person once Jio fell asleep and got rid of the threat

Honey was just checking whether he was dangerous for Jio or not. Otherwise he would've devoured him like what he did with the priest from the previous chapter.