I noticed you said mutants exist, and the new movies will be considered canon in this role play. 
I had an idea where MC would be a clone of Gambit. Maybe one of the kids from Logan. Not sure, still piecing it together. 
He arrives in New York when he’s about sixteen. Without any real way to support himself, he starts busking. Doing “street magic” and card tricks to earn a couple bucks. His powers and general lack of wealth or a home, land him in with a rough crowd. A crowd that seem his powers and quick fingers useful. Working as a low level thief and street magician for a few years before the snap, and subsequently learning magic. Scanning most of the times and texts into his iPhone and stealing a magic tarot deck, that lead to some even better card based combat scenes.  
Maybe he has one of these to print sigils on cards to combine magic with his mutant power. 
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