Are you...sure you want to stop, Snape? You're looking a bit strained. Sirius, meanwhile, crosses a leg over the shaft of the broom and regards the floating potion's master in relative comfort.

"Oh, let's not let anything so crass as debt come between us, Severus, not when we've turned over this beautiful new leaf." He smiles expansively, but it comes nowhere near his eyes.

"I'll call this an even exchange for the present I got you earlier. Such a shame you don't seem to be using it, though. I rather thought a chemistry set that let you make your own shampoo would improve everyone's lives all around, but I apologize if the skills required were a bit beyond your abilities."