How to make a vassal

[Jong]

Can you hand them 1000 florins at a time, repeatedly, as a gift to get them to be more favorable to you? Then ask for vassalage? I haven't tried it, but that might work. Same thing we do with the Pope to make him happy.

It seems that when they hate you, they will refuse pure money bribes. Region gifts combined with money were the only thing I got them to accept.

[zstajerski]

Take their Capital, and offer it back to them for vassalage!!!

Works almost every time( sometimes you need some money though)

[sapi]

I don't think storming the capital is the best way to get a faction to like you