Remy LeBeau, the mutant who would later become Gambit, was abandoned at birth by his birth father due to his unusual red-on-black eyes (they believed their child was of satanic origins). He was stolen from a New Orleans orphanage by the Thieves Guild and given to Antiquary, a collector of children, who considered Remy a perfect work of art. There he was given the name Remy and the title Le Diable Blanc (The White Devil), because of an old Guild Prophecy that spoke of a white devil.
However, Jean-Luc LeBeau greatly disliked the idea of the child being in Antiquary 's care, and arranged for Remy to grow up being watched by a gang of street thieves known as Fagan's Mob instead. At age eight, Remy met and befriended a young girl named Bella Donna. A few days later, he was taken in and adopted by the leader of the Thieves Guild, Jean-Luc himself, after a failed pickpocket attempt which had been secretly arranged by Jean to meet with the young mutant.
His powers manifested in his teenage years, however he kept it secret from those around him. When Remy was 15, he went along with his cousin Etienne Marceaux on the Thieves Guilds ritual initiation called the "Tithing".
They were ordered to steal from an immortal mutant known as Candra, but were subdued. Candra then recognized Remy from a battle she fought with him in her past, that being Remy's future (he travels to the 19th century during his tenure with the X-men). She sold the two boys to a mutant gangster and child slave trader named The Pig, who planned on selling them to HYDRA as boy soldiers. Remy escaped his holding pen and tried to escape, but when Pig caught up with the boys, Remy picked up a playing card, charged it and threw it in Pig's face, thus discovering his new signature move. In an attempt to escape, they both jumped off a cliff into the sea. Remy was rescued by the Guild, but Etienne drowned.
The Thieves Guild was at war with the Assassin's Guild, but Remy was meant to be the one to unite the two guilds through an arranged marriage to the head of the Assassin's Guild's granddaughter, Bella Donna, whom he had befriended as a child years before. On his wedding day, Remy was challenged to a duel by Bella Donna's brother, Julien. When Remy killed him in self-defense, he was banished to ease the tension between the Guilds.
For a time, Gambit traveled the world and lived as a professional thief. He also befriended the Marauder known as Scalphunter. As Gambit's power grew out of control, it was Scalphunter who directed Gambit to Mr. Sinister for help in controlling his mutant power. Sinister removed some brain tissue in order to reduce Remy's power to a more controllable level. In return, Remy owed a debt to Sinister, and he became one of his henchmen.
He also had to put together a team of mutants that would become the Marauders. What Remy did not realize was that their goal was to kill all of the Morlocks, (see Mutant Massacre) a group of mutants who lived underground, because Mr. Sinister had discovered that they were created by someone using his own genetic works. Once he realized what was happening, Remy tried to put a stop to this plan and was almost killed by the mutant Sabretooth. He managed to survive, and rescue the Morlock child who would one day become Marrow.
Later, Remy met a de-aged Storm of the mutant team known as the X-Men. As a result of her transformation into a child, Storm had amnesia. Gambit helped free her from the psionic entity, the Shadow King, as well as Nanny & Orphan Maker. The two formed a partnership as thieves and Gambit looked after her as they worked their way along the Gulf of Mexico, robbing people as they went. When Storm was returned to her true self, she lobbied for Remy to be admitted into the X-Men. Looking to make up for his part in the Mutant Massacre years ago, he accepted and joined the X-men.
Soon after his joining the team, his partner Storm was kidnapped by Genoshan Magistrates. Gambit aided the X-Men along with other X-teams in their battle to free their teammates.
source: http://www.angelfire.com/comics/benriely/gambit.html
http://marvel.wikia.com/Remy_LeBeau_%28Earth-616%29
http://www.comicvine.com/gambit/4005-1499/