He told Hermione four days later, in the prefects’ study room on the fifth floor, with the door locked, the windows charmed, and Neville standing guard politely as a silent, mutely supportive insurance policy.
He had not, in those four days, slept very well.
He had tested his cast on a field mouse with a leg fracture, in the same clearing in the forest, two nights after the owl.
The mouse had also flown – metaphorically, at least.
The mouse had hopped off the handkerchief and into the brush, and had disappeared briskly back to its business.
He had documented it.
He had confirmed that the cast still produced the same colour and effect.
He also had gone to Snape, on Tuesday evening, in the dungeon office with the kettle and the leather chair, and told him, and Snape had listened with his fingers steepled and his eyes half-closed, and Snape had told him, in turn, at the very end of the conversation, *good.
Now Granger.* So.
Now Granger.
He laid the notebook in front of her on the table between them.
He had flagged the relevant sections of notes with strips of parchment for quick reference.
He had her open the notebook.
He let her read.
She read for a long time.
She did not say anything.
He watched her read.
He also watched her read the owl notes, the mouse notes, and his notes regarding the framework afterwards.
And he watched her, for the first time in their two year friendship, not understand something that was explicitly in front of her – which was something he had not, he realized, seen her do before, and which was, he found, an adjustment for her.
She was, normally, exceptionally good at understanding on first reading.
The reversed AK was not a concept for first reading.
She flipped back the pages.
She reread it.
She looked up.
“Cael.” “Yes.” “You —” “Indeed.” “This —” “Yes.” “Cael, this is —” “I know.” “I’m — give me a moment.” She put both of her hands, flat, on the notebook on the table.
She took a breath for ten seconds.
He watched her work herself, systematically, through learn-it-accept-it-contextualize-it-framing stages of absorption.
She was, right now, in the process of contextualizing.
Within an hour she would be ready to move to framing.
He was prepared to wait for an hour.
“All right,” “All right, Cael.
The — the model.
The framework predicted that an inverted lethal spell would — would do what, precisely?
We never wrote it down explicitly.
We — *I* — wrote in the paper that *the system predicts that lethal-vector inversions would produce vitality-vector restoration*, and I was being conservative with my terminology, because I did not want to claim too much.
But that’s *exactly* what this *is*.
This is — ” “Yes.” “It’s not a healing potion.” “It’s not a healing potion.” “A healing potion restores to baseline, right?
And — and the bird — the bird was *perfect*.
The bird was — ” “Restored to its peak.
Yes.
That was the prediction.” “And the cast is *not* dangerous to a healthy subject.” “That I haven’t confirmed.
The system predicts that on a healthy subject it will produce a temporary enhancement effect, rather than damage — because there’s no ‘unmaking’ for an inversion to invert, and the magic doesn’t really have anywhere else to go but to create a vitality burst at the surface level.” “You haven’t tested it.” “No.” “Cael, we have to test it.” “I know.
I want to test it on myself.” She did not, immediately, say anything.
She was, he realized, formulating her argument.
“That’s — Cael, that is the *least* responsible —” “Hermione.
Listen.
I am the only possible healthy subject for which consent is structurally complete.
I cannot ask someone else to undergo a Killing Curse, reversed or otherwise, even with a full briefing.
I cannot use an animal as a subject.
The only person at Hogwarts, who can volunteer for a Killing Curse and understand *what the cast is supposed to do*, is me.
I will conduct the experiment in a controlled setting.
You and Neville will be in the hall outside.
You will have the coin-charm activated for Pomfrey.
If I fail to emerge from the room within ninety seconds you call Pomfrey immediately.
The failure mode predicted by the system on a healthy subject is *not death.* The failure mode is… *what, exactly*… the system does not predict any failure modes on a healthy subject.
I am asking you to support me in conducting a test which the system predicts to be safe and that, should it confirm our predictions, will give us the evidence we need.” She closed her eyes.
She opened them.
“Cael.
I don’t like it.” “I know.” “I think it’s reckless.” “It is.
But it’s also the version of reckless that carries *least* additional risk.
Because if I don’t conduct this experiment on myself, I won’t conduct it at all, and we will have developed a system for healing that can be deployed during an emergency, but which remains untested in a controlled environment.
I will not use it for a patient until I have done that testing.
The testing must happen.
The only person it can happen *to* is me.” “Cael — ” “I’m asking you to support me.
Not to talk me out of it.
I’m running the test.
Would you join me in the hall?” She looked at him for a while.
“I am going to tell you,” she said, finally, “that I think this is reckless.” “I’ve heard you.” “And I’m going to come.” “Thank you.” “And we’re going to discuss the *approach*, seriously, before we conduct the test, because if we go into that room with just my predictions in my head, and not yours, then if anything happens, you won’t be able to help.” “All right.” She opened her notebook — her personal one, the much larger notebook she had started using last spring — to a blank page.
She picked up her quill.
She gave him the look that *go*.
He went.
He reviewed the approach with her, seriously, for the first time.
He talked her through the active restoration process.
He also discussed the predictions for the healthy subject case.
And he also discussed, ultimately, why it was necessary, he projected, to have four tiers of calibrated application — peak, elevated, moderate, minimal — and what they each would be expected to achieve in specific circumstances.
He discussed everything, actually, for two hours solid.
Hermione wrote, without pause, filling six pages by the end of it.
At the end of two hours, she looked up at him.
“Cael.” “Yes.” “This — this is going to be — if it works like this — if the cast on a healthy subject is really what we think it is… this is *medicine*, Cael.” “Yes.” “If this works… if what we’re predicting is true… if the cast on a healthy subject really turns out to be what it appears to be… this is going to be — Pomfrey — Pomfrey is going to *cry*.” “Pomfrey is going to do no such thing.” “She may well.” “Pomfrey is going to look at me and say, *drink something hot.*” “Yes, alright, fair.” She closed her notebook.
She placed her hands, firmly, on it.
She looked at him.
“When are we going to do the test?” “Saturday morning.” “All right.” “Hermione.” “Yes.” “Thank you.” She gave him one brisk nod.
She did not say *you’re welcome*.
She did not need to.
She picked up her notebook.
She put it in her bag.
She left.
Neville entered from the hallway.
“That was a lengthy discussion.” “Yes.” “Are we going to conduct the test Saturday?” “We are going to conduct the test on Saturday.” “All right.” Cael picked up his notebook.
He placed it in his own bag.
He looked at Neville, who was, as usual, exactly where he needed to be, asking exactly the right questions without saying any more than he needed to.
“Neville.” “Yeah.” “Thank you.” “For what.” “For not trying to talk me out of it.” “Cael, it’s your magic.
It’s your test.
You are not the kind of person who needs talking out of things you’ve thought about for two years.
I’m not going to start treating you differently just because this project is bigger than the last project.
I’ll be in the hall with you.
I’ll hold the coin-charm for Pomfrey.
If something happens to you I’ll run to Pomfrey faster than you have ever seen me run.
That’s my role in this.
I understand my role.” Cael stared at him for a long while.
“You are,” he said, finally, “the best friend I have in this world.” Neville blushed, suddenly, bright red.
“Don’t be — Cael, don’t be — that’s *Hermione*, Cael, I’m not… Hermione is…” “Hermione is also.
You are not in competition.
I stated a fact.
Stop arguing.” “I’m not arguing.” “You are now arguing about whether you are arguing.” “I’m not arguing.” “Calm yourself.” “I’m *fine*.
*Fine.* Let’s go to dinner.” They went to dinner.
Neville stopped blushing sometime around the second course.
Cael consumed three servings.
Hermione made a note, across the table, of the fact that he was not planning on eating breakfast the next Saturday.
Tonight, he planned on consuming breakfast ahead of time.
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