Personality in Sapkowski's Novels
Geralt of Rivia is portrayed as a taciturn, cunning, and mercenary protagonist. He rarely partakes in the joys of friendship and human company (save his closest friends like Dandelion), although he has been known to enjoy women (such as Yennefer, his love) or a good tankard now and then. He does few favors and travels throughout Temeria in search of coin. Despite putting on a brave front for most of Sapkowski's 'The Last Wish', he has introspective moments where he struggles, like many witchers, for relevance and importance in a world that needs them less and less as there are fewer monsters left to kill. He also has to handle discrimination in varying degrees, from the curious looks he attracts by virtue of being an albino and a mutant (albeit a non-congenital one), being paid meager sums for his work, to hostile bigotry.
He does exhibit signs of basic humanity, as he constantly seeks to choose 'the lesser evil' in the moral quagmires he faces throughout the novels. He can also be considered somewhat of a pacifist, as he usually chooses the path of least resistance or violence, even if it means endangering his life and limb. He is not, however, opposed to choosing inaction, even if this will cause others to suffer or die. He rarely chooses this path, however, and will gladly intervene if an innocent is attacked. That being said, if a fight is taking place between equal forces he will often not choose a side, knowing his intervention would only cause more suffering due to his incredible combat abilities.
Abilities and Talents
Like most witchers, Geralt is especially gifted in swordplay. This allows him to easily dispatch multiple groups of foes, be it human or demonic. Being subjected to a great manner of experiments, innoculations, herbal preparations (The Trial of the Grasses) and the like have also granted him inhuman reflexes, dexterity and the ability to manipulate his pupils for improved night-vision. The trade-off for this power is that he is rendered infertile. His extremely resilient immune system responded very well to these experiments, prompting his guild masters to subject him to even more dangerous ones that granted him powers far beyond the ken of his peers, although they adversely affected his body's melanin production and made him an albino. The combination of his prowess, detached personality, and his appearance have thus earned him the moniker 'Gwynbleidd' (The White Wolf).
He displays a deep knowledge of alchemy, and is able to brew a great many potions for his battles and contracts. Geralt is also well read, and has an above-average understanding of the arts, religions (although he is an atheist), and sciences of Temeria.
Geralt was born to sorceress Visenna and (presumably) a warrior called Korin. He was then sent to Kaer Mohan - the Witchers' fortress after his birth. Despite not being of Rivian descent, he chose his simple surname after his masters deemed his first choice (Geralt Roger Eric du Haute-Bellegarde) silly and pretentious. After undergoing training under Vesemir among others, he finally received his witcher's medallion and started travelling Temeria on his horse Plotka (Roach, a name he would later give all his subsequent horses).
He eventually gained repute as a peerless warrior and problem-solver. Of especial mention was his ability to cure Princess Adda, daughter of the King of Temeria of her striga curse.
Despite being killed at the novels' conclusion in a hate-motivated slaughter of non-humans, he emerges relatively unscathed (although having a bout of amnesia) and back at Kaer Mohan. Before he gets a chance to piece together what has happened to him, a group of humans later known to him as the Salamandra attack the witchers' haven, in an attempt to steal the information and equipment stored in their laboratory. Assisted by Triss Merigold, the witchers manage to drive off the Salamandra, and soon after it is decided that in order to gather information on their enemy, it is best if each witcher scours a different area of the world. It is at this point that Geralt sets out for Vizima, the home of King Foltest.Once he arrives at Vizima however, he is not granted access to the city for fear of the plague. In order to gain access, Geralt must assist the people of the outskirts with a demon that's been terrorizing the land. Reluctantly he takes up the task, only to discover later on that the demon was given life by the committed evil of humans.
Regardless, he is granted facetious access to Vizima, only to be captured and imprisoned, though he earns his freedom once more by disposing of a monster spotted in the sewers. Geralt then continues his search for the Salamandra, seeking the help of a local detective who's family had also been destroyed by the group. The detective instructs Geralt to get acquainted with several of his suspects, if they are to find one that can give them information about their common foe. During his search, Geralt begins to question the nature of his existence more and more, truly wondering whether or not a witcher still has a place in the world, given that humans have become the real monsters, and they hide behind the law or ideals in order to promulgate their evil. Ultimately, Geralt discovers that his cooperation with the detective had been compromised, since he pieces together clues that lead him to believe the detective is dead and the person pretending to be him is quite likely the enemy he seeks. Geralt then decides to lure his enemy into a trap by not revealing the information he knew, but the leader of the Salamandra managed to escape unscathed.
As his quest continues, Geralt discovers that he must choose a side in the conflict between the humans and the Scoia'tael, since being neutral is no longer optional in a world that requires allies merely to survive; nor will his memory be restored, if he decides to ignore to take a stance for the things he truly believes in. Though the player has the option of siding with either the Scoia'tael or the Flaming Rose, given Geralt's background and the default status of the story depicted in the game's sequel, it is safe to assume that Geralt feels his alienation from humanity makes him more akin to the elves, dwarves and other non-humans, and thus strives to assist them in their ordeal, ultimately leading to a massive slaughter of the Flaming Rose.
Ultimately, Geralt discovers that the true leader behind the Salamandra is Grand Master of the Flaming Rose (who had also been conspiring with Princess Adda to usurp King Foltest), and sets out to kill him, goal which he achieves.
At the end of the game, Geralt stops an assassination attempt on King Foltest's life. However, he then discovers that the dead assassin may have been a witcher as well, strange fact which sets the stage for the sequel, Assassin of Kings.
The Witcher 2: Assassins of Kings
Following on from the first game, Geralt is employed as Foltests' right hand man, his job to protect the King as he sees him as a 'lucky charm' during the prologue of the game, Geralt saves the King's life on more than one occasion. The goal of the battle they are in is to take back the city and find the royal children.
As they're storming the city a dragon attacks, Geralt and Foltest are split from the rest of the party and head towards where the royal children are hidden. When they eventually reach the tower where the royal children are being protect, Geralt stays back as Foltest greets his children. The blind monk protecting them warns of guards approaching the tower and ushers the children to safety. As Foltest is walking out of the room, the monk gets up and takes off his bandage, revealing he isn't blind. Geralt realises this all too late as the assassin slices the King's throat. As Geralt turns to chase the Kingslayer he notices he is a Witcher too. The assassin is a huge mass of a man, much larger than Geralt.
Geralt chases the killer but he jumps out of a window of the tower into the water below, where he escapes; aided by the Scoi'a'tel. As he inspects the King's lifeless body, guards rush in to see Geralt and he is falsely accused of killing the King. Whilst in prison Geralt vows to find the Kingslayer and clear his own name. The rest of the game continues on from this story.
The Witcher 3: Wild Hunt
Following a little while after the events of the second game. Geralt continues his hunt for Yennefer after fully retrieving his memory, this is his only agenda. He is done with the political quarells of The Northern Kingdoms, and is back on track to fulfill his desire of finding his long lost love. Confirmed to be the last Witcher game starring Geralt as the main character, it will be the grand finale concluding his story, and for the first time in the series' history is to be open-world.