The first thing that strikes me is the vague sense of disorientation. Exhaustion. Giggly? Not quite. I'm not a man who could ever be described as "giggling", ever.

  The second thing that strikes me is that it's been thirty minutes and I'm not dead yet. Is this the afterlife? If it is, it feels awfully like the cave I was trying to die in. And since when does the afterlife have my exact model of cell phone telling me that thirty-ish minutes passed?

  I sit up. That's wrong too. I shouldn't be able to sit up. The CO2 levels in here should have knocked me unconscious within minutes, killed me within ten. I did the research. I picked this spot specifically because the geology was reliable.

  The air still tastes wrong. Thick and sweet and heavy. But my lungs are processing it anyway, apparently. Or not processing it. I'm not sure what's happening. I feel like I've been holding my breath for a very long time, except I haven't been.

  I turn on my flashlight. The cave is exactly as I left it. Dirt floor, damp walls, dead end. Nothing has changed except me.

  I should be dead.

  I'm not dead.

  I crawl toward the entrance, flashlight beam bouncing off the walls, and the air gets easier to breathe as I ascend. By the time I reach the mouth of the cave, my head is clearing, the strange fuzzy sweetness fading into normal mountain air. I sit at the entrance for a while, looking at the same trees and sky and distant mountains I looked at two days ago, trying to understand what just happened.

  The obvious explanation is that I miscalculated. The CO2 levels weren't as high as I thought. The cave wasn't as deadly as the research suggested. I got lucky - or unlucky, depending on perspective.

  But that doesn't feel right. I was in there for over thirty minutes. I felt the air change. I felt myself slipping away. Something should have happened.

  I look at my hands. They're shaking slightly. There's a sharp rock near my left knee, edges jagged from some ancient geological process. Without really thinking about it, I pick it up and draw it across my palm.

  The pain is immediate and clarifying. Blood wells up, bright red, exactly like it should. I watch it pool in the lines of my hand, watch it drip onto the dirt.

  And then I watch it stop.

  Not clot. Not scab over. The wound just... closes. The skin knits itself back together like a zipper being pulled shut, smooth and seamless, leaving nothing behind. Not even a scar. The whole process takes maybe fifteen seconds.

  I stare at my palm for a long time.

  The hike back to my cabin takes two hours. I move slowly, partly because my coordination is still unreliable, partly because I keep stopping to test things.

  I cut my arm. It heals.

  I scrape my knee on a fallen log. It heals.

  I bite the inside of my cheek hard enough to draw blood. It heals.

  By the time I reach the cabin, I have a working hypothesis: something happened in that cave. Something changed me. I don't know what, or how, or why, but I'm no longer operating under normal biological parameters.

  The first thing I do is call my father.

  "Josh?" He sounds exhausted. It's late afternoon in Boston, which means he's probably still at work, which means he saw my name on the caller ID and stepped away from whatever he was doing to answer. "Are you okay?"

  "I'm fine," I say. "I think. Something happened."

  A pause. "What kind of something?"

  "I'm not sure yet. I need to come home. I need to see a doctor."

  "You're coming home?" His voice cracks slightly on the last word. I realize, belatedly, that he thought this call might be a goodbye. That every time his phone rings, some part of him is bracing for the news that his son is dead.

  "I'm coming home," I confirm. "I'll explain when I get there. I don't understand it myself yet."

  "Okay." He takes a breath. "Okay. Do you need me to book you a flight?"

  "I can handle it. I'll text you the details."

  "Josh?"

  "Yeah?"

  "I'm glad you called."

  I don't know what to say to that, so I just say "Me too" and hang up.

  The flight back to Boston is uneventful. I spend most of it staring out the window, watching the country scroll by beneath me, thinking about what comes next.

  The logical thing to do is get tested. MRI, bloodwork, the whole battery. See if whatever happened in the cave shows up on the scans. See if the CJD is still there, still progressing, still eating my brain one misfolded protein at a time.

  If you encounter this story on Amazon, note that it's taken without permission from the author. Report it.

  I'm not optimistic. Powers - and that's what this is, I'm fairly certain - don't cure diseases. They give you tools to survive immediate threats. The cave was an immediate threat. The CO2 was killing me, so my body learned how to not need oxygen. Organ failure was the immediate threat, the slow snipping of every wire, so now I'm... what, unkillable? God, I hope not. Maybe I don't need organs. Maybe this is something weirder. Why the regeneration? What an odd circumstance.

  But either way, CJD isn't an immediate threat. CJD is a slow erosion, months of gradual decline. Whatever process granted me these abilities probably doesn't even recognize it as a danger. The prions will keep misfolding. My brain will keep deteriorating. I'll still die - just slower, and stranger, and with the added indignity of being something not quite human in the meantime.

  Still. I should get tested. I should know for sure.

  Dr. Kessler agrees to see me on short notice. I suspect my father called ahead, because she has my file open when I arrive and her expression is carefully neutral in a way that suggests she's been briefed on something unusual.

  "Joshua," she says. "Your father mentioned something happened in California."

  "Something happened," I agree. "I'm not sure what."

  "Can you describe it?"

  I tell her about the cave. The CO2. The thirty minutes I spent unconscious in an atmosphere that should have killed me. The healing. I show her my palm - unmarked, unscathed, no trace of the cuts I made just two days ago.

  She listens without interrupting. I don't see the judgement in her eyes when I tell her that I went out west fully planning to simply lie down and die somewhere pleasant. When I'm done, she's quiet for a long moment.

  "I promise we will get around to this. However, medical ethics dictates that I must ask if you're still feeling suicidal. Do you feel like you are currently a threat to yourself or others?" she asks, firm but quiet.

  "Myself? No. Others? I really couldn't say," I answer as honestly as I can.

  "You're describing a spontaneous metahuman adaptation," she says after another fifteen seconds of near silence, staring at her clipboard. "I've seen two of them during one of my fellowship rotations. Regenerative capabilities, possibly respiratory adaptation. It's rare, but not unheard of. The near-death trigger is consistent with what we know about how these abilities typically emerge. Everyone calls it an 'Activation Event' but we generally call it 'spontaneous metahuman adaptation' in the medical sciences."

  "I know," I say. "What I need to know is whether it changes my prognosis."

  She hesitates. That's not a good sign.

  "We should run some tests," she says. "Updated MRI, full bloodwork, CSF panel. See where we are."

  "You don't think it will help."

  "I don't know. That's the honest answer." She folds her hands on the desk. "Metahuman abilities are still poorly understood. The regeneration you're describing might slow the progression, or it might not affect it at all. Prion diseases don't work like normal tissue damage. They're not wounds that can be healed - they're a fundamental error in protein folding that propagates through the brain. Even if your body can regenerate neurons, it might just be creating new neurons for the prions to destroy."

  I nod. That's approximately what I expected.

  "Let's run the tests," I say. "I want to know what I'm dealing with."

  The results come back three days later. Dr. Kessler calls me into her office, and this time she doesn't bother with the neutral expression. She just looks confused.

  "I don't know how to explain this," she says.

  "Try."

  She turns her monitor so I can see the scans. Two images side by side - my brain from three weeks ago, and my brain from yesterday.

  "This is your initial scan," she says, pointing to the left image. "Classic CJD presentation. Spongiform changes in the cortex, signal abnormalities in the basal ganglia, early involvement of the thalamus."

  I nod. I've seen these images before. The Swiss cheese brain. The death sentence in grayscale.

  "This is yesterday's scan."

  The right image looks... the same. Maybe slightly worse, if anything. The spongiform patches seem a little more extensive, the signal abnormalities a little more pronounced.

  "The disease is still progressing," I say.

  "Yes." Dr. Kessler frowns at the screen. "But that's not the confusing part. Look at the CSF results."

  She pulls up another window. Numbers, mostly meaningless to me, but she highlights a few lines.

  "These are your protein markers. 14-3-3, tau, S100B - the things we use to track prion activity." She points. "They're through the roof. Higher than your initial tests. Higher than I've ever seen, actually."

  "Meaning the disease is accelerating."

  "Meaning the disease should have killed you already." She looks at me. "Joshua, based on these numbers, you should be in a vegetative state right now. The level of neural destruction these markers indicate is incompatible with... this." She gestures at me—sitting upright, speaking coherently, very much alive.

  "But I feel fine," I say. "Better than fine. Clearer than I've felt in weeks."

  "I know. That's what I can't explain." She turns back to the screen, pulling up both scans side by side. "And then there's this. These scans look like two different patients."

  I lean forward. "What do you mean?"

  "CJD doesn't migrate. It doesn't retreat from areas it's already colonized. Once the spongiform changes set in, they're permanent. The damage spreads outward from initial sites - it's predictable, trackable." She points to the left image. "Three weeks ago, classic presentation. Left temporal lobe heavily affected, early involvement in the thalamus, basal ganglia showing signal abnormalities."

  Her finger moves to the right image. "Yesterday? The left temporal looks almost normal. Clean signal where there should be holes. But now the right parietal - which was completely unaffected before - is showing early spongiform changes." She shakes her head. "It's like the disease is... chasing something. And whatever it's chasing keeps moving."

  "That's not how prions work," I say.

  "No. It's not." She stares at the scans. "It's like I'm looking at two different brains. Which is impossible. You can't just... grow a new brain."

  The room is quiet for a moment. I can feel her academic curiosity warring with her clinical training - the part of her that wants to understand fighting the part that knows she's supposed to be helping me.

  I stare at the scans. The Swiss cheese brain, still full of holes. Still dying. But also, apparently, rearranging itself. I clench my hands and start laughing. "Man. I get the good roll to luck into the one thing that would stop me from killing myself. And then I just keep dying anyway?" I sort of half-declare, half-ask. Then, I bury my head into my hands. I'm not really crying, but I'm not stopping my nails from digging into my forehead either, leaving little red half-moons that bead up for a split second and then just close back shut.

  Yeah, I've noticed how little pain I seem to be feeling recently. But she doesn't need to hear that yet. I pull my nails down, leaving tiny red tears in my skin. Not clawmarks. Just little scrapes. "Isn't it ridiculous?"

  "I'm sorry, Joshua. I wish I had better news to tell you," she answers, running her hands through her hair. "I've applied to a grant from the Department of Applied Anomalous Sciences - I think they would be willing to finance more aggressive testing. As your doctor, it's my job to make sure that you have quality of life for as long as possible. If your metahuman abilities are just masking the full extent of your condition, it's my professional opinion that we should be doing everything we can to give you an informed idea of how much time you have left."

  "So I don't think I'm fine, try to get back to life, and then just fall over like a Monty Python character?" I ask.

  She inhales through her nose. "More or less."