He does! "What good cause?"

So she explains about the petness of her firstie and how far Black has escalated and Michael's participation.

"Slytherin. Yeah, go for it." Polyjuice is provided.

"Thank you!"

And she finds a good time for Michael to get in Black's way and some pigment to make his wand superficially resemble hers for a little while.

And Michael borrows a set of her robes and takes the Polyjuice and bumps into Black in the hallway with a bookbag slung over his shoulder, and blocks the immediate motion to throw him against the wall -

Black frowns, does it again -

The girl who looks like Genevieve Stoller sets down the bookbag, shaking. "It's bad form to leap to curses without a challenge, you know."

"You want me to duel you? Swan thinks you're cute but she can't walk in a straight line, she won't take over when you die."

"Yes, I want to duel you. Cricket can be my second, he has a bite."

Black blinks at her. "Mudblood, I'd just kill you. Don't be a fucking Gryffindor about it -"

Genevieve Stoller has adorably wide eyes and is trembling and is waving her wand like she hasn't the faintest idea how to use it.  "Challenge me or cut it out."

"- you wanna be too dumb to live, fine."

She bows solemnly. Stalks back five paces. 

The common room is looking on in mingled concern and confusion. 

"Mew."

"Don't be silly, kitty, I'm sure he figures out which end of his wand is the handle in some more intelligent manner than asking his mirror every morning."

Black shoots a glare at her. "Where," he snarls at Stoller, "and when -"

"Here and now."

He bows. He raises his wand, slashes-

- gets blocked -

- again - 

- gets blocked -

"Wingardium Leviosa," says Stoller proudly, picking up a corner of his robes and levitating it six inches.

Black blinks at her disbelievingly. "Diffindo, Escelpsis."

She dodges. "Expelliarmus!!"

That he deigns to block, using a sweeping motion to knock her off her feet at the same time. She tumbles. "Wingardium Leviosa," she says again, rolling to her feet and catching a different corner of his robes, "Wingardium Leviosa, Tarantallegra -"

Now he looks disgusted. The next Diffindo, dodged again, leaves a gaping slash in the wall. The ground turns to intensely sticky tar so she has to stop dodging -

- she seems unaffected, for some reason -

- four different bolts of purple light arc towards her, so even an experienced witch couldn't block them all - she blocks two, evades one, takes a long ugly slash on her cheek - "Wingardium Leviosa!" And she turns the ground beneath him to oil - he loses his balance but his robes are being levitated in four different places and now he's dangling from them -

"Petrificus Totalus," cries Genevieve triumphantly, at an angle he can't block from. She trots up to him. She takes his wand. "Um," she says. "I have a question about duelling?"

"What's your question?"

"Do I have to kill him? I mean, he implied it was a duel to the death but that seems like a bit much, honestly. He thought I wasn't a witch and I bet he's not confused anymore."

"By dueling etiquette you could kill him if you wanted, but it would be against school rules, so you should probably let him live."

"Mrow."

"Yes, it is very magnanimous of her considering how many rules have previously been broken in this series of events!"

"I don't want detention," she says agreeably, and picks up her bookbag, and leaves. 

Anybody looking likely to unpetrify Black soon?

Several people are looking distinctly suspicious but most of them are just shellshocked. No one is making any moves towards Black. (The ground beneath him stopped being oil as soon as the duel was over.)

Good. Miranda goes to make sure the handoff of Genevieve's possessions is handled unsuspiciously.

Michael is unPolyjuiced and grinning and handing Genevieve Black's wand along with her robes. "Hey, Swan."

"That was brilliant."

"It was a pleasure. Don't try that at home," he tells Genevieve, "I was fifth-year before I could sustain four Wingardium Leviosas with enough strength to hold someone up and by then you'll know better spells for it."

"I understand."

"And you shouldn't keep his wand for long - not sure if you can get away with making him say please, but you could owl it to him at breakfast or something."

She nods solemnly. "Thank you, Miranda."

"You're welcome."

She mails Black's wand to him at breakfast.

He does not harass her further.

He does say to Swan - "I know it wasn't her."

"Gosh, what makes you say that?"