Courier

Jacob Gavin Jr. (aka Courier) is a mutant who has mental awareness of his body at the cellular level which allows him to adapt and regenerate damaged or parts of himself as well as rearrange his molecules into different configurations.

she was hired by New Son to help her and was sent to retrieve some technology from the High Evolutionary. she got caught and provided the mission for Gambit to pay off his debt to New Son when he was rescued. He was Gambit's contact with New Son and relayed the missions to Gambit and they became friends.

Courier became, permantly, a young woman because of a shapeshift in Victorian England that went wrong. Sinister then injected him with a substance that caused his body to revert to a fluid form, in which Sinister set his default state to female, which he assumed it to be.