felix is friends with all of the kitchen staff, because he regularly sneaks down there on his good days.
felix is friends with most of the palace staff tbh bc 1) andrew is an asshole and he feels bad that they have to deal with him, 2) it’s way easier for him to not get in trouble for things when the staff is on his side, 3) he doesn’t really have any other friend options??? like it’s not exactly like he’s supposed to leave the castle (though he sneaks out at every opportunity), and 4) he’s just genuinely a nice person and he sees no reason to be a dick to the staff. unlike some people.
andrew would 100% murder their parents to get the throne sooner if he thought he could get away with it. he currently doesn’t see it as an option.
however, andrew doesn’t see felix as any sort of threat to his power? so he... kind of cares about him in this verse. more than in most, anyway.
felix has super complicated feelings about andrew tbh. they were close when they were little but he knows andrew has grown into a god awful human being and he’s not sure what to do with this information.
despite the fact that they do care about each other more than usual, if it came down to their brother vs something they care about (andrew vs the kingdom; felix vs the throne) neither of them would pick their sibling.