Vanilla uses a unique method to allow you to persuade your heroes to join your kingdom without needing to barter with them. It uses a combination of a dialogue tree and a list of conditions that must be met for the lords to join your kingdom. If the player meets all the conditions, then the character will join your kingdom, but if not, then the player will have to offer a bribe to the character, in order to get them to join.

In the Honorbound mod, you can use a similar method, but the conditions are expanded upon, there is more dialogue and it is easier to understand.