Influence

Influence represents the contribution of a character to the success of their faction, usually earned mostly by fighting in wars. You also gain a bit of influence simply by virtue of holding and governing a fief. It represents political capital, dues paid, favors in the favor bank - all the terms used to represent the currency of power. You spend it to get people to assist you in your campaigns, do you favors, and support your candidacy for titles and fiefs. No one is ever forced to give you what you want when you spend influence - but you do put them under a moral obligation, and they'll look bad if they don't.