[h1][img]http://i1383.photobucket.com/albums/ah281/Q-C0ntinuum/BlessedWraith%20Weaver%20-%20Copy_zps7aq7ebmi.jpg[/img] BlessedWraith (Weaver)[/h1]
You might be overthinking it. A subdermal implant is definitely going to leave some discomfort; especially if it was implanted by untrained personnel. Christian would be very acutely aware of its presence. It's not a great leap of logic for him to assume he's been chipped, especially with what he heard right before he blacked out. So that's totally IC for you to do that.

The best move for him, right now, would be to go off the grid. If it were any normal card, then I'd advise against using it. But, since it's run through a shell company (remember, these cards were meant to be a discreet form of allowance for people on the run), I doubt that any person could accidentally discover it. You'd have to be specifically searching for it, which would mean you'd have to know who your enemy is. Mantovani isn't even sure this group exists yet, so him discovering those transactions is unlikely at best.

Right now, you have a blank check. Your character could make any number of moves. Have fun with it. Run with it. Surprise us.