"Boy!"

The boy just walking into the shop has not been paying attention to this exchange!

He looks like he's probably a first year. He is, however, wearing robes, so he's probably not muggleborn.

"I'll be with you in a moment, dear," the witch says. "You are complicating this, but alright."

The boy waves at the newcomer—

—and is no longer a boy.

The newcomer pauses, just about to wave, and then… proceeds to wave, somewhat bemused.

"Now hold still! I'm already going to have to do this twice, don't make me do it more times."

The girl obeys and holds still, and various tape measures start examining her.

The boy waits curiously.

"Hi! I'm Sadde," the girl calls. Madam Malkins shoots her a sharp look but given that she didn't actually move doesn't say anything.

"Anthony," he responds. "I've never met a metamorphmagus before."

"I hadn't ever met a magical person other than myself before, so I think you're still winning."

"Hold still!" chides Madam Malkins.

"Sorry."

"… Oh? Huh. Even rarer to be a muggle-raised metamorphmagus."

"Muggleborn, even."

"I'm personally not muggleborn," he says. "That was probably clear though."

He gestures to the robes he's wearing.

"Yes, it was. Where're your parents?"

"Mum left me to go robe shopping while she catches up with some people."

"Oh. My mum's buying Potions ingredients for me."

"Can you turn into a boy now, dear?" asks Madam Malkins.

"Sure."

"I don't think I've ever heard of someone swapping gender. Not as a metamorphmagus, at least."

"Swapping gender happens amongst muggles," she explains, "but I hadn't ever heard of someone who did it magically before."

Pause. "How do they do it? Without magic, I mean."

"Makeup. Clothes. Mannerisms."

"Oh," he says. "That's– sort of a shame?"

"Kinda is, yeah. People who don't change and are just one thing all the time can do some kinds of surgery but it's not very good."

"Surgery with– like, knives and stuff, okay, I don't really know why I'm asking about this."

"Not exactly knives, more like scalpels, which are really tiny—" She pinches the air to show how tiny, and Madam Malkins chides her again.