"We haven't met no," Sirius replies, stepping closer once Newt's turned around. His lips twist into a half-grin at the urging to drop the formality and he nods in acknowledgment. "Name's Sirius. I'm... I'm a friend of Kieren Walker's." After a slight hesitation, his lips twisting into a deeper frown, he amends, "Boyfriend, actually. And he's a patient of yours, is he not?"

It's still strange to him, this notion of Muggle science. Even after seeing it in action, witnessing with his own eyes the effect of the pills on Kieren.

Or, rather, the effect without them. And when they've gone wrong.