I've seen a few fics where Credence, still an obscurial, uses his dark powers to protect Newt. They're all amazing and you should read them immediately.

That said, I'd love to see a similar scenario with Credence protecting Graves -- some wizard that he's arrested comes back for revenge while Graves, Credence, and Newt are out together. Graves, the badass Auror that he is, takes the brunt of the damage until Credence just snaps and takes care of their attacker. Then, it's up to Newt and Graves to talk him back down.