"Good evening," says a woman whose eyes are not quite correct, as Professor McGonagall's own eyes begin to inform her that she is standing on a drizzly Cornish beach. "I hope that my... invitation... did not cause you any terrible inconvenience?"

"Invitation?" she asks neutrally, with a raised eyebrow generations have feared. 

"The ritual which I performed, pulling you into this History. The question is something of a formality, as the ritual can only find someone at significant risk of death – but denying one's rightful death can, sometimes, be nearly as hostile as providing it."

A genteel smile, to Minerva's eyebrow. Fewer people have known to fear this expression, but they have feared it for centuries.

"I much prefer being alive, so thank you. What is 'this History'?"

"The world is governed by the Hours of the Mansus and their cohort. I am given to understand that some worlds operate under the paradigm that... 'what happens, happened'? It is not thus, here. Our past is curated by the Hours. But the Hours could never agree on one History. There are five Histories regarded as true, and others... less true. One may travel between them, with the proper invocations. Currently, we stand in a deeply heterodox pseudo-History in which human life was wiped out by a century of winter following the mutilation of the Sun. It is not a cheery place, but it has the virtue of making it very easy to ward off eavesdropping."

Yes, that sounds like the sort of thing that would happen with that amount of irresponsible time travel! It is nonetheless concerning.

"I see," she says disapprovingly. "Dare I hope that you have brought me here to restore some semblance of order?"

There's a flicker of a smile. "I cannot say that thought crossed my mind... but that is exactly why I brought you here. Something needs to change, and we are all too set in our ways. And there is an exellent opportunity opening up to do something about it."

She gestures to a crumbling wreck of a castle on a cliff nearby, not wholly dissimilar to the false Hogwarts shown to Muggles. "Hush House is one of the branches of the Watchman's Tree, those libraries with the right to house books with secrets which could quake reality's foundation. It has lain in ruins for decades, but a new Librarian has been sent to curate it. Unfortunately, her ship capsized, and even now she lies, concussed and dying of exposure, elsewhen on this selfsame beach. The villagers know she is coming, but they do not know her face. You see the opportunity, I trust?"

"Take me to her at once; I know field medicine." She could probably just say 'healing spells', this woman clearly knows about magic to some extent, but the caution is automatic. Regardless, she's not going to impersonate a woman she could instead rescue.

The woman laughs in ungraceful shock, for a moment, then claps her hands. "Very well! If you insist, you may become her savior, rather than become her; perhaps it will be to your advantage. You may tell her, if she asks, that you were sent by Rowena. And you should know that if your efforts please me, I will clear your road home... but if they do not, I will not devour your heart or any silly thing like that. I haven't the time."

She takes a strange little clockwork out of her pocket and tosses it to the ground, where it ticktickticks until

she is not where she was, though she was where she is.

Her patient lies at her feet, eyes open, barely breathing. Her benefactress is nowhere to be seen.

Minerva is no Healer; Poppy can and does solve problems that would be beyond her knowledge, and the experts at St Mungos with their specialized equipment can do even more. But this isn't a splinching, or an attempt to Polyjuice into an animal, or spell-resistant dragonpox, or absent bones. It's just some blunt-force trauma and hypothermia, easily mended. (The way she responds to the spells suggests some non-human ancestry, but that's none of Minerva's business.)

(approval)

(annoyance)

Sharp inhale, and the poor woman's heart's back to beating like it's supposed to. She opens her eyes.

"...had I any expectation of someone to save my life," she murmurs, "you would break it."

Then she retches quantities of seawater, as expected.

Minerva neatly steps back to avoid being vomited on, rather than Vanishing the mess; her wand is hidden in her sleeve. (This doesn't make her not look like an obvious witch, but it's enough for the legalities if this woman is a muggle--and if she's even still somewhere the Statute applies.) 

When the woman is done retching, she offers her a hand up. "Minerva McGonagall. Pleased to meet you, Ms. --?"

"Blackwood," she says, shaking and then accepting the hand, then brushing some sand from her posterior. "Artemis Blackwood – legally still Mrs. Henry Blackwood, I do prefer to get that out of the way, he is deceased which is very sad and you do not need to apologize about it. It is certainly my pleasure to meet you, Ms McGonagall, as I would else be very dead."

. . . She doesn't have an easy way to confirm whether Blackwood is a witch. It's usually obvious from context, and when it isn't, mentioning her job is sufficient--if someone asks what Hogwarts is, they're a muggle. But she's far enough from home that that's unlikely to work. There's always 'just bring it up, obliviate if necessary' but she'd rather wait and see if she comes up with something more elegant or less rude. 

"I met someone a short time ago who called herself Rowena and implied you knew who she was." That'll get some clarity if there's any in that direction to be had.

"...we are acquainted."

Had she asked Professors Snape and Karkaroff whether they had met, the response on both sides might have been similar.

Not unsurprising, given Rowena's casual suggestion that Minerva take advantage of Blackwood's death to impersonate her. "I would like to know more about her capabilities and motives, if it would be convenient."

"Her capabilities? She has lived like a cockroach on the shoe of history since before the Romans finished falling, even though you won't find more than half a dozen in the world who wouldn't like her better dead. In some magics, it's easier to list what she cannot do. But she had to reach the top fast, and the path she took limits her to those magics she mastered."

She unearths a flask from her pocket and drinks a mouth-clearing swig of alcohol now that her stomach has had a moment to recover. "As to her motives... you must understand, anyone who lives even a hundred years can get through their reasonable aims. You just run out. I think any immortal, when you cut down to the bone, wants to fix it, where 'it' is everything. Or just everything that hurt me, when I lived."

She lets that linger a moment, then: "What about you? I imagine you have capabilities and motives of your own."