My work didn't stop at demon blood.
Far from it.
While experiments continued—slow, controlled, deliberate—I began building something just as important.
A body of knowledge.
From my past life, I carried the understanding of a modern physician: anatomy, pathology, sterilization, pharmacology. Concepts so far beyond this era that even fragments would be revolutionary.
And from Tom Riddle, I possessed something equally invaluable.
An eidetic memory.
I could recall books I'd read decades ago word for word. Spell diagrams. Ritual sequences. Faces. Dates. Failures.
But even that had limits.
Memory—no matter how perfect—was still bound to time.
After a few hundred years, even flawless recall would blur at the edges. Details would lose precision. Context would fade. And I refused to let centuries of work vanish simply because I trusted my own mind too much.
So I wrote.
Constantly.
I recreated advanced drugs from my modern world using what ingredients this era allowed—antibiotics in primitive but effective forms, pain suppressants that didn't rely on alcohol or opium, antiseptics refined through both chemistry and magic.
I documented everything.
Dosages. Side effects. Failures. Improvements.
Medical techniques followed. Proper wound closure. Internal bleeding management. Infection prevention. Even basic surgical protocols that this era had never formalized.
Then I went further.
I dissected the dead.
Not out of cruelty—but necessity.
Human corpses first, acquired discreetly, respectfully. I mapped muscles, nerves, organs, vessels with painstaking care. Each structure drawn by hand, enchanted ink preserving clarity for generations.
Advanced medical diagrams filled entire volumes.
Then came demons.
Their physiology was unlike anything human. Organs that regenerated even after removal. Blood vessels that pulsed with curse energy. Structures that existed solely to distribute Muzan's influence throughout the body.
I catalogued it all.
One book became three.
Three became a shelf.
Titles etched carefully into leather-bound spines:
Principles of Human AnatomyFoundations of Practical MedicineAdvanced Alchemical PharmacologyDemon Physiology and Regenerative BiologyOn the Nature of the Curse
Some books were purely scientific.
Others blended magic, medicine, and theory in ways that would terrify this era's scholars.
And that was fine.
I wasn't writing for now.
I was writing for the future.
These books were backups—for me, yes—but also something more. If I succeeded… if I lived long enough… then one day, I could choose to let others learn.
Carefully.
Selectively.
Knowledge was power, and power given freely was how civilizations collapsed.
Still, the thought lingered as I placed another completed volume on the shelf.
Even if I vanished tomorrow…
Even if I failed…
These books would remain.
A record that humanity had once stood on the edge of something greater—and that someone had tried to drag them forward.
I ran my fingers along the spines, magic humming faintly through the runes I'd embedded into each cover.
Preservation charms. Fire resistance. Decay prevention.
History-proof.
"Even gods are forgotten," I murmured softly.
"But knowledge doesn't have to be."
And with that, I returned to my work—pen in one hand, vial of demon blood in the other—building a future that would not disappear simply because time demanded it.