Disposition is a numerical representation of an NPC's friendliness toward the Player Character. Low disposition can result in negative effects and dialogue, while high disposition may earn you discounts, quests, and gifts.
Skyrim differs from its predecessors in that disposition unlocks the marriage option. Completing quests, hiring individuals and other tasks will raise some individual's disposition to a level necessary for marriage. However due to the fact that there are no charm based spells that directly influence disposition in a form other than calm/frenzy, spells cannot be used to influence disposition for marriage.
 Relationship Rank
The default relationship rank is 0 (Acquaintance) and it can vary between -4 and 4.
 Quest Rewards
Several quests and favors influence the relationship rank of NPCs, usually when the quest is successfully completed. This is documented on the quest page in the following way:
- The rank is set to friend, no matter what it was before. Sometimes numbers other than 1 appear, the rank is set accordingly.
- The rank is set to friend, if it was acquaintance before. Otherwise nothing happens.
- min 1
- The rank is set to friend, if it was below before. A higher rank remains unchanged.
Other actions influencing the relationship rank:
- Gaining a permanent follower will make him an ally, if the rank was in the range of 0 and 2 before. Dismissing him doesn't change the relationship. For animal followers the initial rank is irrelevant.
- Investing in a merchant will make him a friend if he was an acquaintance before.
- Killing someone who has a high relationship with another NPC will cause that NPC's disposition towards you to fall below 0.