http://mountandblade.wikia.com/wiki/Relationship
"Your Relationship towards a vassal, faction, town, or village exhibits how much they trust or like you. Supporting them usually improves your relationship with them, while fighting or disappointing them harms it.
While your character's relationship to factions and towns/villages always starts at 0, vassals can start with a better or worse impression on you, based on their personalities. Relation can range from -100 to +100. Note that once your Relationship with a vassal reaches +100, it sometimes doesn't deteriorate as it usually would. For example, a vassal with a relationship of +100 toward you may not mind if you give other vassals fiefs.
Relationship affects your interactions with other vassals, and becomes very important if you start your own Kingdom. A very positive relationship with a vassal, for example, will allow you to talk in private with any vassal, giving you a chance to convert them to your kingdom. A very negative one, on the other hand, could cause them to hire assassins.
Having a positive relationship with a married lady will allow you to ask them to improve your relationship with a vassal of the faction who currently has a negative relation with you by sending them gifts of 1000-3000 denars, boosting your relationship with them by +1 per 1000 denars.
If you have any negative relationship with factions, you will be at war with them, and they may attack you at any time.
A negative relationship with a village will prevent you from recruiting there, while a very positive one increases the possible number of recruits gained, as well as their tier.
Negative relationship with a town or its lord prevents you from buying land for a Productive Enterprise, while positive relationship improves prices.
There are several other parties you can increase your relationship with, including Tavern Keepers and Manhunters, but this has no noticeable impact on the game."
Relationship with Factions:
- Protect villagers on the overland map +4
- Rushing to the aid of a vassal in danger +4
- Release a faction's imprisoned lord from a castle or town +2
- Attacking a vassal -1
- Capturing a vassal -3
- Reject peace offer as king -5