So yeah, if you really want relation for w/e reason, just use the console commands. The only thing that seems to raise relations is releasing them after a fight, for a measly +3, yay now I'm only -97! And that only works if they're enemies. Giving them fiefs via barter does not raise relations, giving troops to their fiefs doesn't help, hell i'm the damn king and I'm barred from entering castles they own. My own vassals all instantly hate me if I give any fief to anyone that isn't them, even when the game only gives me the option to give fiefs to the same exact two vassals without any option to give to someone else. Settlement notables all hate you and I'm never allowed to take any quests from them.
You also get -100 for basically everyone all the time just for existing.
Relation seems rather useless anyways, you can still recruit someone if they have -100 for a vassal.
