Well. That's sweet, and that lost puppy look is definitely irresistible. That's got him smiling with a bit of surprise on his own face.

"...Yeah, Pete. We're friends." That feels important to assure him of, first, "'nd I guess if you-- want to help. There's a few on my back that're hard to reach."

So he'll unscrew the cap and offer the jar back to Peter so he can take off his shirt. Shifting so he can offer his back a little better to his friend comes after a tentative moment.

It's a little better on his back. The bruises here look a little older, like they'd come first. There's still plenty of large, ugly splotches, but they're not as fresh. The worse ones are spread across his torso, not as big as the ones on his back but vividly purple, obviously newer. Sirius will be taking care of those himself.

He manages a tentative smile over his shoulder at Peter, after a breath.

"....Thanks, by the way. You're the best."