And another. And another.

  They emerge slowly. Bloated things that used to be human, skin the gray-white of drowned flesh. Maintenance uniforms hanging off them in tatters. Bodies marinating in sewer water for weeks, maybe longer. They look like bad debt given form. Something that should have been written off, still accumulating.

  Twenty of them. More, thirty. Pulling themselves from the pipes, dropping into the water, beginning to move toward the center of the chamber.

  I take the time to count them. Every single one. Commit the number to memory.

  Thirty-four.

  Some might have been maintenance workers who strayed too far. Others might have been looking for the ones who disappeared. Thirty-four people I could have saved if I'd killed this thing the first time. Or the second. Or the third. Or the fourth.

  The interest of my failures, compounding.

  They move toward Sofia.

  She doesn't see them yet. She's looking up at me, waiting for a signal, trusting that I'm checking an exit rather than watching something unfold.

  The first shambler reaches the edge of the moss-light. Sofia's head turns. Her whole body goes rigid.

  "Don't move." I pitch it low, praying it reaches her and nothing else.

  They haven't noticed me yet. I need to keep it that way.

  She begins hyperventilating. I can see it from here. The rapid rise and fall of her chest. The whites of her eyes panicked under the moss-light. But she's not running. Not screaming. Doing exactly what I told her.

  Good, her odds were getting better, that she might survive this.

  The shamblers spread out. A loose circle, tightening. They move with glacial patience, feet dragging through the water, arms hanging limp. No hurry or coordination, not yet. Simply bodies being pulled along by something that doesn't need them to be fast.

  Not yet.

  I swipe away the notification. The answer is trembling in the water below me. Shaking hard enough I can see it from the ladder.

  I could drop now. Twelve feet to the water line, a couple more to get in front of her, I could be swinging before the swarm fully converges. Drawing aggro. Buying her time to run.

  But the core would stay hidden. Even if I could kill all the shamblers until my stamina bottoms out. The core would find a way to make more. We both die down here, and Lily's fever hits 110 tonight with no one coming back.

  Mentally I focus of the concept of the core of the Grudge, I activate [Analytical Strike]

  The percentage appears in my peripheral. A stacking 1.8% damage with each second of observation.

  I force myself to wait. Let the swarm commit to a single point. Force the core to extend its control radius, stretch itself thin across the thirty or forty hosts I see down there, let them all focus on one target. All to create an opening that may finally let me deal with the problem.

  Sofia's survival window at current water depth, 91 to 120 seconds once submerged. Call it ninety, a conservative estimate, she deserves that much at least.

  The reasoning is reconcilable, barely. A thirty-five second margin for locating the core, closing distance, and executing before her lungs give out.

  One of the shamblers brushes past her. A string of gray sludge trails across her sleeve.

  She looks down at it.

  She screams.

  The sound fills the chamber. Bounces off every surface. Travels down pipes and tunnels into darkness I can't see.

  The shamblers stop.

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  Then they start running.

  Not shambling anymore. Not slow. They move with horrible, jerking speed, converging on Sofia from every direction, mouths opening, arms reaching, bodies colliding as they swarm toward the source of the sound.

  She disappears beneath them all.

  One moment she's standing by the ladder, screaming. The next, she's gone, buried under a pile of waterlogged corpses, dragged down by dozens of grasping hands, her scream cut off by the sheer weight of bodies.

  I recheck my calculations again. She has a Constitution of 12. Water depth at the center is forty-ish inches, considering the weight of thirty to forty hosts distributed across her surface area…

  Less if she doesn’t find air before going under. Assuming the pressure of the dog pile doesn't crack her ribs first. Assuming the System enhancement doesn't step in to help her deal with the trauma. Assuming she has the willpower to keep fighting back even when she’ll feel like death is certain.

  Too many assumptions. The margin I calculated isn't a margin. It's a prayer dressed up as arithmetic.

  I could still drop. Abandon the ability. Abandon the charge. It would be so easy to start killing shamblers and hope the core panics, exposing itself early. But hope is not a strategy. Hope is what people use when they've stopped considering the broader reasons that are driving them forward.

  I can’t drop. Not for me, not for her, not for Lily, not for anyone infected below.

  The pile stops writhing.

  Thirty-six seconds since she has gone under. Fifty-four to eighty-four seconds remaining.

  My jaw aches. I've been clenching it hard enough to crack enamel. My hands are white on the rungs. The percentage keeps climbing and I keep watching and somewhere beneath that pile a woman who trusted me to check an exit is running out of oxygen because I decided her survival window was an acceptable variable in my damage calculation.

  I used to watch positions tick up like this. Different numbers, same patience, same sick knot in my stomach when the timing had to be perfect and the cost of being wrong was someone else's retirement fund.

  This is worse though. This is watching the number and knowing exactly what’ll cost someone that I’ve met personally and choosing to keep watching anyway.

  Forty-two to seventy-two seconds left. Call it forty. Round down. Assume the worst. Always assume the worst.

  Somehow I’m reminded then of proportionality. Of minimum effective force.

  Of how I tell myself that's what separates necessary action from cruelty. I tell myself I only take what I need, only hurt what I have to, only go as far as the situation demands.

  But I’ve defined "minimum" so far as assuming I'd be the one paying the cost.

  What's the minimum when I’m making someone else pay it? When my logic, when my reasoning forces someone to drown for thirty more seconds because the damage bonus matters more than her oxygen? Is that proportional? Or is it just arithmetic dressed up as ethics?

  I tell myself a lot of things while the percentage climbs.

  Enough.

  I grip the brush handle.

  The ability cuts through the noise. Suddenly I'm not looking at a dark pipe full of shadows. I'm seeing a path, a trajectory, an arc. The optimal execution, traced in gold from my position to a point three feet inside the eastern drainage pipe.

  Not the center of the mass. Lower instead, left of where I was looking.

  The System corrects my assumptions. I'll take it.

  I launch.

  Twenty feet of drop. The air rushes past. The brush handle angled ahead of me. Bristles first. Somehow not the stupidest weapon I've ever used, aimed at a spot I can only see because of my ability.

  I hit the water hard. The impact drives the air from my lungs, sends a shockwave through the chamber, but I'm already moving, wading, stumbling, driving forward into the pipe where the Grudge is hiding.

  The sludge is thick here. Waist-deep muck that grabs at my boots, slows every step, fills the air with the stench of rot and decay. Light barely penetrates. Without my Ability, without the System, I’d be fighting blind.

  But I’m not.

  I’m guided by the fading echo of [Pragmatic Hunter]'s direction.

  The brush hits something solid then.

  I sweep.

  Bristles drag through layers of accumulated filth, sewage, algae, decomposed matter that doesn't bear thinking about. The resistance is wrong, at first, too heavy, too sluggish. Like the sludge is refusing to move, like its mud. I feel doubt slip into my mind but I treat it like it’s an old friend. I’m familiar with these tricks. I know this mud, is not mud, is not sludge and that it's holding onto something.

  I sweep again, harder this time.

  A flash of light surface, faint and crystalline. Sparkling, trying to disappear.

  There you are!

  The sludge surges.

  Not passive anymore. It rises like a wave, trying to bury the brush, trying to bury me.

  I feel it climbing my chest, thick, cold and heavy in a way that has nothing to do with mass. And somewhere in the chamber behind me I hear splashing… shamblers pulling themselves off Sofia's body, turning, redirecting toward this new threat.

  Toward me.

  The bristles find the crystal again. I feel it through the handle. Something hard and smooth, something that pulses with a rhythm that might be a heartbeat. I pin it against the pipe floor, lean my weight into the handle, and drag it towards me.

  The sludge screams.

  Not a sound. Not exactly. More like a pressure in my skull, a frequency that bypasses my ears and hits something deeper. The shamblers in the chamber convulse in unison, their empty mouths opening, their ruined throats producing a chorus of wet, gurgling shrieks.

  I don't stop.