Civilization 6's cast of leaders are a colorful bunch of historical figures that represent the face of their people, but there's more to them than just their aesthetic value. Each leader brings specific bonuses to the table based on their historical achievements and personality. More importantly, these personalities also drive the grand strategy of the AI civs.
If you're going to play effectively against the computer, you'll need to know what motivates these leaders, how you can cosy up to them and make them like you, and how to avoid pissing them off.
Teddy Roosevelt (America)
Agenda: Big Stick Policy
Teddy Roosevelt wants to keep his continents peaceful. He hates it when wars are started on a continent he's based on, or against city-states in general. So if you're a warmonger on a continent occupied by America, prepare for trouble from Teddy. On the other hand, if you can provoke another Civ into attacking you (for example, by manipulating them according the agendas detailed in this article), then Roosevelt will ally with you to put down the aggressor.
Agenda: Ayyubid Dynasty
Saladin wants to be worshipped in many cities and likes a civilization that follows his religion. He dislikes civilizations following other religions, or civilizations waging war on followers of his religion.
If you want to cultivate Arabia as an ally, you'd better learn to sing along with Saladin's choir, as he'll be friendly and defend you from aggressors. If you can't see philosophically eye-to-eye, then be careful about attacking Saladin's worshippers in arms.
Agenda: Gifts for the Tloatoani
The mighty Montezuma has expensive tastes, but game recognizes game, and he likes civs who have the same Luxury resources he does. He will try to collect every Luxury resource available and gets jealous if it looks like someone is out-doing him. Montezuma dislikes civs who attain a new Luxury resource he has not collected yet.
Pedro II (Brazil)
Agenda: Patron of the Arts
Pedro practices his penchant for patronage by appropriating Great People. He likes civs who are not competing for Great People and will recruit Great People whenever possible. Pedro dislikes it when other civs pinch Great People from him. Your relationship with Pedro is going to be based around these individuals. If Great People are important for your strategy, try to take them early and make plans for things to get rough with Brazil.
Qin Shi Huang (China)
Agenda: Wall of 10,000 Li
Shown above auditioning for Ancient Aliens, Chinese Emperor Qin treasures his wonders and wants to have the most in the game. His special builder units help him get those wonders built early, so China will be at an advantage, building wonders at every opportunity. Qin likes civs who won't compete with him for wonders and hates losing a wonder to another civ.
Agenda: Queen of the Nile
How do you impress a lady like Cleopatra? Turns out she might have a thing for uniforms. The Queen of the Nile likes civs with powerful militaries, and will try to ally with them to avoid conflict. Don't want Cleopatra comin' at ya? Approach her with a strong military force. On the other hand, while she makes sure get on the good side of civs with a strong army, she reserves her contempt for civs with weak militaries.
Agenda: Sun Never Sets
Queen Victoria's agenda represents Britain at the height of its imperial ambitions. Queen Vic is friendly to civs from her home continent but she desires to expand, colonizing the map. Consequently, she doesn’t like civs on continents where England has no city. If you don't start on the same continent as England, prepare to have your homeland invaded by those pesky Brits, or face the Queen's wrath. If it comes to that, don't expect much home turf advantage. England gains free units when it settles on new continents, and the unique redcoat unit gains bonuses when fighting abroad.
Catherine di Medici (France)
Agenda: Black Queen
In contrast to the aggressive Queen Victoria, Catherine prefers soft power. She will attempt to gain as many spies and as much diplomatic access as she can. Keep your eye out for espionage when Catherine's about, and take care to cultivate your own Spies and diplomacy if you want to get friendly. Civs who ignore espionage commit the ultimate faux pas, and offend The Black Queen.
Frederick Barbarossa (Germany)
Agenda: Iron Crown
Barbarossa's agenda is based around your attitude to those irritatingly independent-minded City States. Frederick will be friendly to civs who do not make deals with city-states. But you'll piss him off if you become a Suzerain of a city-state or if you conquer them. If you have ambitions to control the City States, be prepared to face the Holy Roman Empire.
Queen Gorgo (Greece)
Agenda: With Your Shield Or On It
Queen Gorgo of Sparta follows the militaristic line one would expect given her origins. She will never give up items when making peace deals and respects other civs with a similar attitude. Gorgo will not respect civs who have capitulated to an enemy, or never gone to war in the first place.
Agenda: Delian League
The gentler, more gregarious Greek, Athenian Pericles keeps it more friendly than Gorgos, but that doesn't mean you can't make him angry. He likes to cultivate relationships with city-states and will take offense if you compete with him for the allegiance of any city states that he has a relationship with.
Gandhi's agenda may come as a surprise to fans of the Civilization franchise, where Gandhi is famous for being trigger-happy with nuclear weapons. But Civ 6's Gandhi is geared towards peace and religious tolerance. He will never declare war if there's a possibility he could be branded a warmonger, and be friendly towards peaceful civs.
Although Gandhi is slated to hate warmongers, only time will tell if he still has that hidden enthusiasm for pressing the red button. Just because Gandhi is peaceful, that's no reason to ignore India either, as their bonuses give them a strong incentive to rush for a religious victory while the world is distracted by making war around them.
Hojo Tokimune (Japan)
Tokimune's espousal of Bushido means that he likes a strong warrior culture, but with an emphasis on the 'culture'. To impress the shikken, you'll need a strong military and a strong Faith/Culture output. If you have a strong military but but weak Faith/Culture, Tokimune will despise you for the barbarous brutes that you are.
Mvemba a Nzinga (Kongo)
Agenda: Enthusiastic Disciple
Mvemba a Nzinga's agenda is an interesting one. He likes civs to bring Religion to the Kongo, and dislikes civs that have founded a Religion but not brought it to a Kongolese city. To get into his good books, you need to bring your Good Book to his cities. Because his civ gains the beliefs of all religions that are established in a majority of Kongolese cities, this can help strengthen your ally.
Harald Hardrada (Norway)
Agenda: Last Viking King
Hardrada's vikings gain great bonuses geared towards raiding the costs, so he will predictably build a large navy. Harald respects civs who are similarly married to the sea, but bullies civs with a weak navy. Even if you don't want to shake hands with Harald, a strong navy might be necessary to take him down.
Agenda: Optimus Princeps
Similar to England, Rome's AI in the form of Trajan is an aggressive conqueror of territory. It's go big or go Rome with Trajan on the field, as he dislikes weak civs with little territory, and might decide you'll benefit from incorporation into his empire.
Peter the Great (Russia)
Under Peter's leadership, Russia gains benefits from trade routes to more advanced civs. So Peter is friendly to those civs that are ahead of him in Science and Culture. Unfortunately, backwards civs that are lacking in Science and Culture are going to be given the cold shoulder.
Agenda: Backstab Averse
Much like your teenage sister on social media, Tomyris hates backstabbers and fake ppl, but treat her right and you'll be bffs forever. Tomyris is a straight shooter, and likes civs who are her declared friend. She reserves her hatred for backstabbers who make surprise declarations of war.
Philip II (Spain)
Agenda: Counter Reformer
Similar to Saladin, Phillip 2's Spain follows a strong religious agenda. Phillip 2 is friendly to civilizations who follow the same Religion, and he wants his cities to all follow the same Religion. Try to spread a different religion into his empire, and you'll earn his hatred. When entering into a religious conflict, remember to expect the Spanish Inquisition, whose chief weapon is surprise. Surprise and a combat bonus against players following other religions
Agenda: Ally of Enkidu
Two-thirds god, one-third man, 100% beefcake, the mythical Gilgamesh knows that there's no greater power than friendship. This hero likes civs willing to form a long-term alliance and dislikes anyone denouncing or attacking his friends and allies. Gilgamesh isn't totally unselfish about sticking by his buddies, as Sumeria shares pillage rewards and combat experience with close by allied units during a joint war.