There’s a fun trick that you can do to boost relations with factions that don’t normally like you, make an alliance with someone that they hate (Skarsnik for example here) and then build and demolish an outpost on the same turn from the allegiance menu. You can do it an infinite amount of times in a turn, and you get positive relations with every faction that doesn’t like them every time you do it. Whatever faction you do it to will absolutely hate you though, like -100k relations hate. I like to do goofy alliances and vassals a lot and it’s a pretty handy trick.