There are many stories about Lancelot at Camelot, and they vary according to the source
According to some, at the age of eighteen, Lancelot met his cousins, Bors and Lional, and his half-brother, Ector, and the four men set out for Camelot. Because of King Ban's support for Arthur in his youth, Lancelot was welcomed to Camelot by Arthur and Lancelot was knighted on St. John's Day.
In some versions of the legend, one of Lancelot's first tasks as a knight was to bring Guinevere to Camelot for her wedding to Arthur. During their journey back t Camelot, Guinevere and Lancelot fell in love. In other stories, Guinevere was already Queen when Lancelot arrived, and he became one of the Queen's Knights. Lancelot soon became recognised as the greatest of the knights after successfully completing several quests. Among other adventures, he conquered the guardian of castle called Dolorous Gard, which afterwards became his own home renamed Joyous Gard. Lancelot became a full Knight of the Round Table and Arthur's closest companion.
When Guinevere was abducted by Meliagaunce, Lancelot pursued him in a cart. caught up with him and Meliagaunce's life was only spared after his father, Bagdemagus, pleaded with Guinevere to stop the fight. Later, Meliagaunce accused Guinevere of having an affair with Sir Kay, and Lancelot, as the queen's champion, again ended up fighting Meliagaunce. Again, Bagdemagus pled for his son's life. Eventually, Lancelot slew Meliagaunce in combat at Camelot.
Lancelot helped King Arthur put down the rebellion of Galehaut the Haut Prince, who surrendered to Arthur after being influenced by Lancelot's chivalry in battle. Later Galehaut became Lancelot's close friend and acted as a secret go-between Lancelot and Guinevere.
However lancelot suffered from pangs of conscience over his love for Guinevere and pursued numerous quests in order not to see her. Lancelot visted King Pelles the Grail Guardian and saved his daughter, Elaine of Corbenic, from a vat of boiling water in which she had been imprisoned by a magic spell for several years. Brisen, her nurse, contrived to make Lancelot believe Elaine was Guinevere and he slept with her. This union resulted in Galahad being conceived.
Eventually, he meets Elaine of Astolat, whom he brings home to Joyous Gard. But Lancelot is not happy with her either. Elaine later died because of her unrequited love for Lancelot.
Lancelot's son Galahad then appears at Camelot and together they began their quest for the Holy Grail. Lancelot had several visions of the Grail and finds the door to the chapel in which the grail was kept. However he is prevented from entering the building and discovers that this is because his love for Guinevere, exceeded his love for God.
Lancelot and Guinevere were discovered together in her chamber by Mordred. Lancelot fled and Guinevere was sentenced to burn at the stake. Lancelot returned to rescue Guinevere, accidently killing Agravain, and Gawain's brothers, Gaheris and Gareth in the process.
War between Lancelot and Arthur resulted, but was broken off when Arthur had to return to Camelot to deal with Mordred's rebellion. Hearing of this, Lancelot returned to aid Arthur but arrived too late to save him from a mortal wound. Arthur dies and effectively this is the end of Camelot
Lancelot visited Guinevere, by now a widow in a nunnery at Amesbury, renounced
being a knight, and became a hermit for the rest of his life. He was buried
at Joyous Guard:
Sir Lancelot, knight of the Round Table