"What do you need boy robes for?" inquires Madam Malkins.
"I'm sometimes a boy," the girl explains.
"Surgery with tiny knives." He grimaces a bit. "I haven't really learnt much about muggles."
"How do magical people do it?"
"We go to healers. I'm not sure about for – changing gender, I don't recall having heard about it before."
"I'm done, dear," says Madam Malkins, and she starts busying herself with charming robes to the correct size.
The girl is a girl again, and says, "Well, muggles don't really have healers, we do what we can with what we have. It's a lot, for the record."
"You have – doctors, right? I guess they train to do surgery?"
"Yes, they spend several years training and getting very specialised."
Nod. "So – you only found out about all this recently?"
"Well, I was a metamorphmagus since always. So I kinda knew some kind of magic must exist. But what that kind was, exactly, yeah."
"… I admit I don't know much about metamorphmagi but – were you just a really well-behaved small child?"
She smirks. "No."
"So. Did they just get the Obliviators in a bunch of times, or…?"
"- the who now?"
"Muggleborn, right. There are some people who, uh. 'Clean up' after magical accidents, make sure there aren't people claiming to have seen wizards?"
"...how. Exactly. Do they do that."
"They don't go killing people or anything," he hastens to add. "They… use a spell to make people forget about it."
"They do what?" she shrieks.
"Miss Woods! Control yourself!" Madam Malkins says sharply.
"… I'm guessing you don't actually need it repeated," he says, quietly.
"No. No I don't." She finds somewhere to sit. And sits.
"I don't actually know they did it for you, just –"
"Oh, oh no. They. They definitely - this explains so much -"
"Sorry to be the bearer of bad news."
She buries her face in her hands.
Any chance he can get measured for his robes perhaps maybe?