Every rival holds an opinion of you, from −100 to +100, and none of it is hidden: hover the number on the Lords screen (d) and every cause is itemized.
Where an opinion comes from
Creed. Kin creeds start at +15. The Flame and the Umbra despise each other from −20. Everyone else keeps a wary −5.
Standing. Open war −20. A sworn pact +8. An alliance +18.
Your size. Hold more than 30% of the realm and every lord’s unease grows with your map.
Borders. Two or more shared borders rub, up to −8.
Common cause. Both at war with the leader? +10. Nothing warms like a shared enemy.
Deeds. Everything you do is a ledger entry with its own fading rate. Break an oath and every lord writes it down, not only the one you wronged, and that ink barely fades.
Treaties
Peace. Ends a war. Gold can sweeten a stubborn one.
Pact. Non-aggression, sworn on an existing peace. Breaking it is a deed everyone reads.
Alliance. Grows from a pact, and it is defensive: attack one ally and the other joins the war. Allies also share their eyes: what one sees on the map, both see.
Calling allies to war. Any lord can be called into a war you already fight, with gold to steel their nerve. A refusal is remembered mildly; an answered call warmly.
Gifts and demands. Gifts warm by their weight (up to +20). Demands cost warmth whether paid or refused. Pay them only when the alternative is worse.
When one lord grows too large
Once per game, the realm leagues: if a leader holds 40% of the map (or 34% for ten seasons running), every other lord turns cold toward them at once, and warms toward each other. It is announced in the chronicle like weather.
What moves a rival to accept? Roughly what would move you: peace when they are losing or weary of a long war, a pact from +8 attitude, an alliance from +25. Temperament bends these: a proud lord refuses longer, a greedy one reads the gold first.