Every settlement has their own Relations关系 bar on the same screen that displays Renown and Reputation. All settlements start with the bar at Neutral.
The player can increase and decrease the Relation to each settlement by doing certain Actions. (Table below)
Good 良好Relations关系 improve market prices. (lowers prices for buyable items on markets and increases prices for items that the player wants to sell)
Relations trend towards 50 and these minute shifts in Relations关系 take place at dawn of each day. (applies to both decay and gain, so a settlement at Hostile(0) will take roughly 40 days to reach Threatening(10))
Fortified settlements (Fortified Manor/Castle/Stronghold) are fully affiliated with their Noble House and do not have separate Relations关系 bar unlike non-fortified settlements. Their Relation score is essentially the Relation with the Noble House in question which is used to determine prices.