Cesare Borgia was born in the 1470s in Rome, Italy. His father became Pope Alexander VI and his mother was a noblewoman. Cesare studied law after becoming the Bishop of Pamplona when he was 15 and by the age of 18 he was a Cardinal. It is rumored that Cesare had his brother, Giovanni, who was captain general of the military, assassinated so that Cesare could start his military career.
Cesare's military career was successful, but things went wrong when his father died in 1503. Cesare depended so much on his father, and he was unable to win the favor of the newest Pope, Pius III. Pius III had Cesare arrested, but he escaped. Cesare headed to Romagna, but he was captured again. He was exiled to Spain and imprisoned in a castle where he managed to escape once more. He began fighting for his brother-in-law, who was King John III of Navarre. He died in 1507 in battle.
Assassin's Creed: Brotherhood
After his attempted assassination in the events of Assassin's Creed 2, Rodrigo Borgia retreats from both the public eye and from his machinations as an agent of the video game franchises' main antagonists, the Templars. This leaves his son and leader of the Papal armies, Cesare Borgia as the defacto leader of the repressive Borgia family dynasty which dominates all of Rome.
Cesare's first action since the attempt on Rodrigo's life is mounting an attack on the town of Monteriggioni, where the assassin faction responsible for the plot reside. Here the playable protagonist, Ezio Auditore is forced to flee the villa with his remaining family after his uncle Mario is executed by Cesare, who reacquires a mysterious artifact called the Apple of Eden.
Over the course of the game, Ezio along with the remainder of the Brotherhood operate in the city of Rome, where they work to undermine Cesare's ambitions to dominate all of Italy and Spain. Ezio goes on to remove Borgia Influence from sectors of the city, rebuilding the economy of Rome ruined by the plundering of the corrupt Borgia, and eliminating key members of the Borgia's military along with experimental weaponry developed by Leonardo da Vinci
against his will.
Further power is siphoned away from Cesare by Ezio as the assassin aligns himself with the city's underground factions, cripples the Followers of Romulus
who act as puppets for the Borgia Papacy, ousts Cesare's French allies from Rome and recruits rebelling citizens into the brotherhood to fight the Templars throughout Europe. The erosion of Cesare's power base culminates with Ezio's assassination of Juan Borgia the Elder, of whom was the banker that allocated funds for the city into Cesare's pocket.
Upset over the crippling of the families' rule, Cesare confronts Rodrigo to demand funds for his campaign as well as the Apple of Eden. Rodrigo rejects these demands as he sees that his son eats a poisoned apple, however Cesare's sister and lover Lucrezia alerts him to Rodrigo's attempt to kill him before he has eaten enough to die. Cesare angrily shoves the apple into Rogrigo's mouth, mortally poisoning him. He then interrogates Lucrezia for the location of the Apple of Eden Rodrigo has hid for himself from Cesare. Ezio, who was eavesdropping at the scene on a mission to assassinate Rodrigo questions an upset Lucrezia for the Apple's location, where he then races against Cesare to. Cesare is late to take the Apple before Ezio, who escapes with it despite an onslaught of Borgia troops throughout the city.
Still ailing from the poison ingested, Cesare attempts with futility to rally his demoralized troops to hunt down Ezio and the Brotherhood, who ambush and wipe out the massive contingent of Borgia troops with the power of the Apple. Cesare flees to then appeal to other cardinals for help, where he is rejected on account of the corruption of the Church under the Borgia's rule. In a final bid to remain in control of Rome, Cesare's forces engage in a stand-off with Ezio and his allies just inside the gates of Rome. Despite another staggering defeat, Cesare insists that his colleague Micheletto Corella will arrive with another army of Borgia troops to his aid. He is then shocked to find the arriving army under the command of Fabio Orsini, who arrests Cesare under orders from Pope Julius II for "the crimes of murder, betrayel and incest". As he is dragged away under arrest, Cesare screams in defiance that he will not remain imprisoned and that "[he] will not die
at the hands of man".
Concerned by these last words, Ezio later uses the Apple with reluctance to see a conjured image revealing Cesare's whereabouts. Ezio then leaves Rome, after the Apple's revelation that Cesare would in fact escape captivity. An loyalist to Cesare had thrown a rope for him to climb down and escape the prison where he resided. Ironically, the accomplice would be the one captured and executed for the breakout after Cesare collapsed on him while climbing down the prison complex. Cesare recovered from leg injuries sustained in the fall and went on to lead an Army to retake the Viana Castle from the Count of Lerin for his brother-in-law King John III of Navarre. Cesare had hoped a victory in Viana would gain him the support of the French, allowing for the re-acquisition of Rome and the conquest of Italy and Spain.
It was in the midst of battle where Ezio once again confronted Cesare in a final bid to kill him. Cesare briefly escapes a confrontation with Ezio in the frenzy of the battle before being cornered by the assassin at the castle. In a climactic battle, Ezio defeats Cesare, who even at the mercy of the assassin insists he cannot be killed by man. Frustrated, Ezio throws Cesare over the side of the castle to his death, leaving him "at the hands of fate".