Diplomacy in Stellaris draws on the model of previous Paradox games. Each AI nation has an opinion and relation values which are increased by friendly actions, diplomatic agreements, and agreeable ethics - and decreased by hostile behaviour and incompatible ethics. It should be noted that the dialogue at the initial contact screen has no effect on opinion or further diplomacy.
Many diplomatic actions have a 10-year cooldown once chosen. Some of these are unilateral while others need to be accepted by both sides which becomes a matter of acceptance. Most diplomatic options are only accepted if the target empire holds a neutral (yellow) or better attitude.
During war, the peace and surrenders are available from the war menu.
|Action||Effects||Opinion if active||Trust||Trust Cap||Influence||Requirements|
|Declare War||Enters the Wargoals menu to declare a war.||-50||-2||50||0||No Truce|
|Offer Trade Deal||Allows the negotiation of a one-time deal
Each AI personality has a different acceptance rate for trade deals.
|Declare/End Rivalry||Closes borders and grants the Animosity Casus Belli.||-100||-2||50||+0.5||Relative Power is not Pathetic or Overwhelming
Cannot be lifted for 10 years after declaration
Default Limit of Rivalries is 3 but can be increased via Ethics and Civics
|Insult||Decaying -200 opinion Opinion Modifier.||0||0||50||0|
|Form/Break Defensive Pact||If either empire is attacked the other will join the war as a defender.
Breaking the pact sets a 10 year truce.
|+20||+0.75||100||-1||Neither empire is involved in a war|
|Form/Break Non-Aggression Pact||Both empires will not be able to declare war upon each other.
Breaking the pact sets a 10 year truce
|Form/Break Research Agreement||Applies a 25% bonus to researching technologies discovered by the other party.||0||+0.10||50||-0.25|
|Form/Break Commercial Pact||Both empire will gain the economic bonuses of 10% of each other's Trade Value. Neither empire loses any profit.
If one of the empires built a Branch Office on other other's worlds the former partner will gain the Expropriation Casus Belli.
|0||+0.25||50||-0.25||Neither empire has the Criminal Heritage civic|
|Offer/Break Migration Treaty||Allows the migration of Pops across both empires borders.||0||+0.25||50||0||Empires need to allow Pop Migration
Both empires have planets with at least 20% habitability for the other's species.
Neither empire has the Barbaric Despoilers civic
|Guarantee Independence||The guaranteeing empire will come to the target empire's defense if attacked but not vice versa.
This is the only way to start building trust if the other empire holds a negative attitude.
Revoking the guarantee sets a 10 year truce
|+10||+0.25||50||-0.5||Both empires are independent
The independence of up to 3 empires can be guaranteed
|Support Independence||The supporting empire will join the war against the overlord if the subject starts a war for independence. The supporting empire's power will be added to the relative power of subjects opinion modifier between the subject and the overlord.||+10||+0.25||50||0||Target is a subject|
|Invite to Federation||Forms a new Federation with the Target Empire.||+50||+1||100||-2||The Federation tradition, or founding member has it
Neither empire has the Barbaric Despoilers or Criminal Heritage civics
|Ask to join Federation||Requests to join an already existing Federation.||+50||+1||100||-2||Existing Federation
Federation members must agree by a majority vote.
|Federation Association Status||The empire and the Federation will not be able to declare war upon each other.||+10||+0.50||100||0||The majority of federation members must agree to granting or removing the status but the associate member can cancel it at any time|
|Close/Open Borders||Controls border access. The initial stance is determined by the Initial Border Status policy.||-20||0||50||0||No Truce or Rivalry|
|Ask to be their Vassal/Protectorate/Subsidiary||Turns your empire into a Vassal or Protectorate. Request is only accepted by empires holding a Protective or Domineering attitude, which both require inferior relative power.||0||0||50||0|
|Offer Tribute||Turns your empire into a Tributary. Request is only accepted by empires holding a Protective or Domineering attitude, which both require inferior relative power.||0||0||50||0|
|Demand Vassal/Protectorate/Subsidiary Status||Asks the empire to become your Vassal or Protectorate.
Refusing grants the Subjugation Casus Belli.
|+25||+0.25||50||0||At least Superior Relative Power|
|Demand Tribute||Asks the empire to become your Tributary.
Refusing grants the Subjugation Casus Belli.
|+25||+0.25||50||0||At least Superior Relative Power|
|Release Subject||An overlord can always release a subject. Used to avoid risking wars of independence if the relative power of subjects becomes too great.
Sets a 10 year truce between the overlord and former subject
|Integrate Subject||Integrates a Vassal or Protectorate into the overlord empire.||0||0||50||Variable||Sufficient Influence|
|Request to become AE subject||Become a subject of an Awakened Empire. Awakened Empires holding an Imperious attitude will agree while those holding a Belligerent attitude will prefer a more aggressive subjugation.||0||0||0||0|
The acceptance of diplomatic agreements by computer empires is determined by multiple factors.
The most specific factor that determines an empire's acceptance rate is its AI personality.
Trust, Threat and Distance
Trust is gained slowly by maintaining any form of lasting treaty. The maximum amount of Trust obtainable is limited by the most valuable treaty between both parties. Finishing the Diplomacy tradition tree grants +50 trust cap. Trust decays if there is no new income.
Threat is acquired by conquering systems, starbases and planets as well as by using Colossus weapons. It is seen as a form of aggressive expansion. Threat gain is dependent on the AI empire's personality and distance and reduced by half by existing non-aggression pacts or stronger deals. Shared Threat acts as a positive acceptance modifier for defensive deals.
Distance negatively affects diplomatic deals as empires farther apart in hyperlane jumps are seen as less relevant. If two empires' borders share a hyperlane connection they are considered neighbors and don't suffer distance penalty but have to deal with border friction. Two distant empires that have their owned systems connected via a wormhole are also considered neighbors.
Agreements and Ethics Attraction
Some diplomatic relationships affect the ethics attraction within an Empire. Running deals can have a great impact, based on the empire ethics of the other party - always dragging their own population towards a certain Ethic. The wrong friend can cause great internal issues for an Empire.
- War: Militarist
- Rivalry: Militarist
- Defensive Pact or Federation: Egalitarian, Xenophile, Spiritualist
- Migration Access: Egalitarian, Xenophile, Spiritualist
- Research Agreement: Materialist
- Subject: Spiritualist if the overlord is spiritualist too
Each empire will have a specific attitude towards other empires dictated by their AI personality, diplomatic interactions and the relative power of both empires.
|Attitude||Trade & Pacts||Prefer peace||Other Effects||Requirements||Description|
|Neutral||none||This Empire does not consider us relevant to their interests.|
|Wary||none||inferior relative power and shared border||This Empire maintains a cautious attitude towards us.|
|Receptive||more inclined to accept diplomatic pacts||diplomatic AI personalities||This Empire is interested in closer relations with us.|
|Cordial||more inclined to accept diplomatic pacts||high opinion||This Empire is amenable to peaceful coexistence and trading with us.|
|Friendly||more inclined to accept diplomatic pacts and join a federation||high opinion and successful past diplomacy||This Empire views us as a friend and may be willing to form an alliance with us.|
|Protective||more inclined to accept diplomatic pacts and may ask you to become their subject||high opinion and superior relative power||This Empire believes that we are weak and need their protection.|
|Unfriendly||none||low opinion||This Empire views us with suspicion and mistrust.|
|Rival||none||rival with low opinion||This Empire views us as their rival.|
|Hostile||none||very low opinion||This Empire views us as their enemy. They are likely to attack us if they think they can win.|
|Domineering||only uses the Subjugation Casus Belli||low opinion and Subjugator AI||This Empire believes that we would make a fine vassal.|
|Threatened||none||high threat rating||This Empire views us as a threatening menace.|
|Overlord||none||overlord||This Empire is our overlord.|
|Loyal||none||subject with positive opinion||This subject is loyal to us.|
|Disloyal||considers the relative power of other subjects too||subject with negative opinion||This subject resents its subservience to us.|
|Dismissive||none||Fallen Empire||This Fallen Empire considers us largely beneath their notice.|
|Patronizing||may bestow gifts||Fallen Empire with high opinion||This Fallen Empire views us as errant children in need of their guidance. They may deign to bestow gifts of technology, resources or ships on us.|
|Angry||will send a demand which will grant them Casus Belli if refused||Fallen Empire with low opinion||We have angered this Fallen Empire with our actions, and they may declare war to punish us.|
|Imperious||will ask you to become their subject||Awakened Empire||This Awakened Empire views us as a future subject. They are likely to demand we surrender our independence.|
|Belligerent||none||Awakened Empire whose subject demand was refused||This Awakened Empire views us as a target of conquest. They are likely to attack us.|
|Arrogant||no effect||Awakened Empire overlord||This Awakened Empire views us with dismissive arrogance.|
|Custodial||accepts joining a Federation||Guardian Awakened Empires||This Awakened Empire believes that it needs to protect us from the crisis currently threatening the galaxy. They are likely to attempt to ally us.|
|Enigmatic||opinion is hidden and has no impact||Ancient Caretakers||This Fallen Empire is an ancient artificial intelligence that behaves in a strange and unpredictable manner. We do not know what to expect from it.|
|Berserk||attacks any empire nearby||Malfunctioning Custodians||This Awakened Empire is an ancient artificial intelligence that has gone berserk. It is likely to attack anything and anyone around it.|
Opinion modifying option have no effect in a multiplayer game in relation to human players. However they will take effect if the AI takes over a human player, after the "rejoin Cooldown" has been worked off.
There modifiers are either permanent or will persist until the diplomatic status changes and are the second most important factor in deciding how diplomacy will proceed after a first contact.
|Literary Savior||20 if you return the text during the Prince event|
|Book Burner||-20 if you refuse to return the text during the Prince event|
|Returned Wreckage Cargo||20 if you return the minerals in the wreckage anomaly event|
|Stole Wreckage Cargo||-20 if you claim the minerals in the wreckage anomaly event|
|Nurtured Forebears||100 towards Nivlac Circle if you relocate the Nivlacs in the Impossible Organism event|
|Discarded Forebears||-100 towards Nivlac Circle if you shot the Nivlacs into space in the Impossible Organism event|
|Ketling Planet Subdued||-20 towards Ketling Star Pack for every Ketling system claimed|
These modifiers are temporary and will eventually disappear. However they can also be reinforced and increased up to a certain limit.
Fallen Empires Only
|Failed Major Task||-200||1||-200|
Aside from determining an empire's attitude, opinion also affects certain quests such as The Prince. In addition, a negative opinion can trigger certain events from empires that aren't Pacifist or Fanatic Pacifist.
- An opinion below -50 can trigger a governor assassination event
- An opinion below -100 can trigger an objection to expansion event