Yep he is a red flag, even from the start, bc that's the kind of character he is.
If he isn't a red flag then what kind of story will this make? tbh him being all toxic adds flavor to the story. And ffs, this is FICTION, but some people can't differentiate fiction to reality
If you are at that age that you think this is just as good to be done IRL.
THEN FCK OFF THIS SITE, YOU SHOULDN'T BE READING THIS IN THE FIRST PLACE.
There's a lot of bl or even straight novel/manhwa/hua/ga that is worst than this.
After re-reading it, for red horse obviously they aren't in a relationship, so for him what Dan did is just distraction when he should be focusing on JK's physical health, but on the other hand, even when Dan does his job right he is the one who refuse to listen, to both Dan and the Doctor.
idk what's going on with this red horse dude bro. he is the only character I can't read