Attitude is a game mechanic in Divinity: Original Sin II. The number represents a character's favorability toward a party member, with positive numbers indicating good favorability and negative numbers indicating dislike.
NPC attitude
Attitude affects merchant prices. Traders upcharge their wares if they dislike the party, while discounts are offered if they view the party favorably.
The attitude value reflected in an NPC is specific to the selected party member. This means that an NPC can dislike one party member but like another.
NPC attitude can be increased through dialogue options and offering gifts (through the trading menu). Attitude can be decreased through dialogue and committing crimes.