Gambit’s secret role in helping Mister Sinister set up the Mutant Massacre shattered his relationships and almost doomed his place in the X-Men.
Despite his roguish attitude and shady past, Gambit has grown to become a dedicated and loyal member of the X-Men. But for years after he initially joined the team, Gambit was found to be hiding a genuinely tragic and shocking secret about his connection to one of the greatest tragedies in modern mutant history.
Although he’s since become a veteran hero, Gambit’s role in the “Mutant Massacre” still stands as one of the most devastating betrayals to the ideals of the team in their entire history.
Long before he joined the X-Men, Remy Lebeau traveled the world, perfecting his skills as a thief. As his mutant abilities developed, however, he lost control of his powers. Unexpected help came in the form of Mister Sinister, a mad scientist who’d spent the better part of a century researching mutants and experimenting on them in various forms. He performed emergency surgery on Gambit, removing minor amounts of his grey matter — giving him full control over his powers. In exchange, Gambit serves as Sinister’s agent, completing missions for him around the world. Gambit attempted to quit his employ after rounding up a number of murderous brawlers and assassins, but Sinister forced him to continue helping the group until they completed their own mission.
Gambit was unaware that this group — quickly going by the name of the Marauders — had been assembled to carry out a very deadly mission. Ordered to bring the group to the Morlock Tunnels, Gambit was able to sneak them through the defenses and into the caverns. Unable to hide their mutations, the Morlocks had developed a minor community under the New York City streets. Gambit assumed they would be captured or cataloged by the Marauders. In reality, the group was there to slaughter them — wiping out the Marauders, as they were actually an attempt to replicate Sinister’s own genetic modification work and he sought to destroy all traces that weren’t his own work. Realizing his grave mistake, Gambit moved to stop them.
But he was forced to flee when Sabertooth turned on him and almost slew the Cajun mutant. In the chaos, Gambit was able to only save a single life — a young girl named Sarah, who would grow up to become the X-Man known as Marrow. Gambit would later find himself working with the X-Men, joining their number, and working with the people he’d almost inadvertently doomed by setting off the Mutant Massacre. During his time on the team, Gambit’s mysterious and dark past was hinted at multiple times — but he grew into a dependable hero and even fell in love with his teammate, Rogue. In Uncanny X-Men #350 by Steve Seagle, Joe Madureira, Andy Smith, & Tim Townsend, Gambit finally had to face the music.