[Note: This chapter's primary content has been integrated into the preceding chapter — the Forbidden Forest midnight encounter with Dore, the breakthrough on the Killing Curse mechanics, and the shift to a Horcrux-framework approach. The material flows continuously from Chapter 181.]
The research shifted after that night.
Kevin spent the next several days in the restricted section of the library — with Dumbledore's standing permission, which had been granted in second year and never rescinded — working through every available text on soul mechanics, Horcrux theory, and the specific conditions under which soul separation could be performed without fatal consequence.
The restricted Horcrux volume was dense and unpleasant to read in the specific way that texts written by people who found their subject matter enjoyable always were. Kevin read it with the focused detachment of a researcher taking notes on something distasteful, which was precisely what he was.
What emerged, slowly, was the architecture of a different approach.
Not a modified Killing Curse. Not a weakened Avada Kedavra with the lethal element sanded off. Something new — a spell built from scratch, drawing on the voluntary soul-separation mechanics underlying Horcrux creation, but applied externally. Designed to identify a foreign soul fragment inside a living person, isolate it from the host's own soul, and excise it without touching what was meant to remain.
The theory was clean. The practical application was another matter entirely.
He brought it to Snape on the fourth night.
Snape read his notes in silence. His expression throughout was the one he reserved for students who had done something structurally correct but had also clearly not thought about the consequences.
"This will take months," Snape said.
"I know."
"If you get the targeting wrong, you don't remove the fragment. You damage Potter's actual soul."
"I know."
"And if you get the separation wrong—"
"I know, Professor."
Snape set down the notes. He looked at Kevin with the expression of a man who has been carrying a very heavy thing for a very long time and has just been offered help by someone he's not entirely sure he should trust with it.
"We'll begin the practical work next week," he said. "After I've reviewed your theoretical framework for errors."
"Thank you."
Snape looked at him for a moment longer. "Don't thank me yet," he said.
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