The Underground is infected

CONTENT WARNING! THIS AU INCLUDES:

Body horror

Gore

Suicide ideation

Death

The Underground is infected with a mind controlling fungus! It all started when Papyrus Fell Down in a patch of mushrooms.

In this AU, Frisk comes from a coven of witches.

This AU will become a Charisk AU.

Frisk's four versions of her main outfit and spoilers for certain roles under the cut.

If Chara's the personification of the infection, but it was Papyrus who gave the mycelium sentience...

How does that work?

Okay, so, this is gonna be kinda difficult to explain.

Chara died to the infection as part of The Plan, but the infection affects humans differently than monsters. Instead of shattering after Asriel failed and came back, Chara's soul was absorbed by the mycelium and stored in a kind of stasis until the infection gained sentience.

Then, it used Chara's memories to recreate her body.

“Yeah, pretty much. It's so useful that I don't usually use the real ones.”

Sans and I laugh at that. Grillby returns with our food a few seconds later.

“thanks, g.”

The flaming bartender nods and returns to what he was doing beforehand.

I take a bite of the Dublin Coddle, and my eyes shoot open. “Wooh. That is… *ahem* That has a strong kick to it. It's really spicy.”

“so you don't like it?”

“Quite the opposite! My nickname at the dinner circle back home was Hot Rod because I always put a lot of spices and hot sauce on my food.”

“ah, got it. well, something about food down here. it converts into energy upon swallowing. negates the risk of choking, y'know? that, and it still gives you that ‘full’ feeling.”

“Ooh! I wish human food was like that. I can't tell you how many times my sister Gwenyvalt chokes on her food because she doesn't chew her food enough.”

“gwenyvalt, eh?”

“Yeah. She isn't really my sister; I called her that because I'm from a coven of witches, and members of the coven are sisters, while the leaders of the coven are mothers.”

“huh. interesting. anyway, what else can you do?”

“Uh… not much. There's osteokinesis—”

“hey, me too.”

“Well, of course you have osteokinesis. You're a skeleton. Anyway, I also have the stereotypical dark magic that witches in media have.”

“that's cool. ya sure there's nothing else?”

“Well, I think so. I feel like I'm forgetting something.”

“well, if you forgot, then it's probably not important.”

If Papyrus Falling Down was what triggered the apocalypse, why was his team trying to make fungicide?

Because there had been reports of a fungus that was infecting monsters and turning them into mindless zombies. The infection wasn't contagious, but it was dangerous.

“what do you want me to do about it? barter away my rock collection?”

“What do you mean by barter? Doesn't Fort Wintera have a currency system?”

“We did until Papyrus kicked the bucket in one of his mushroom patches and kicked off the apocalypse. When he croaked, the mushrooms soaked up his dust and formed what's called a Putridian.”

“a putridian is a monster infected by the zombie fungus. rumor has it that there's a ‘human’ out there in the forest. this ‘human’ is actually an acolyte.”

“And I assume an Acolyte is a human Putridian?”

“bingo. anyway, whatcha wanna eat?”

I look at the menu. “Ooh, Dublin Coddle sounds great! I've had it before, but I'm willing to bet it'll taste different because of obvious differences in our societies.”

“hey, dublin coddle sounds great. a double order of dublin coddle please, grillby, and a bottle of brandy for me and… whatcha wanna drink?”

“Water is fine.”

“and water for frisk.”

Grillby nods and goes to the back to prepare our orders.

“so, kid. what magic have ya got?”

“What makes you think I have magic?”

“well, you had to have come from the ruins, and the only way there is through one of the most infected areas in the underground, aside from the wetrock district and the capital.”

“Fine, you got me. I have cleansing magic—doesn't work on sentient beings, sadly—and light magic. I'm also proficient in alchemy and dagger fighting.”

“huh, cool. anything else?”

“Yes. There's the Doppelgänger spell, which is a highly advanced form of magic that creates duplicates of the target. Despite looking and feeling and sounding real, the duplicates are only illusions. Then there's the Post Mortem Recall spell. It allows me to rewind time after getting killed.”

“how far can you rewind?”

“It's not a matter of how far. My SOUL automatically casts the spell moments before it shatters. It sends me back to the last savepoint I interacted with.”

“well, well, well,” a short skeleton dressed in a heavy, navy blue cloak comments as he approaches me. “who do we have here?”

[I'm Frisk,] I sign in Monster Sign Language. [I'm a human. Who are you?]

The skeleton chuckles and says, “i'm sans. sans the skeleton. i'm the jravel of fort wintera, of which we are currently outside the walls of. c'mon, let's get something to eat.”

[That sounds like a good idea.]

Sans leads me into the fort and points out landmarks as he leads me through it, including the shop and inn, the Librarby, the training grounds, and a statue of a tall skeleton wearing a lab coat.

“that statue is of my brother. his name's papyrus. he was the first to turn, but he also led the research team that attempted to develop an effective fungicide. the team failed, and they were all turned as well.”

I nod solemnly, but also with a hint of intrigue.

Eventually, we reach an Irish pub; Sans nods to it and says, “here we are. grillby's.”

My excited smile makes Sans chuckle, and he holds the door open for me. “after you,” he says.

[Thank you,] I sign before entering the pub.

“you're welcome.”

The bartender looks up and brightens upon seeing Sans and me. “Ah sure look who's landed here now,” he says. “A human is it? Well isn't that grand. It's been a good while since I laid eyes on one of your kind.”

“hey, grillby. how's it going?”

“Well hello there, Jravel. I'm grand sure. Are you here to settle up the bill, or are you treating the fresh survivor to a pint?”

Sans chuckles nervously, and I shoot him an incredulous glare. “You're in debt?” I exclaim through clenched teeth.

“so the human speaks; and yes, i'm in debt. so what?”

“You're the Jravel of this fort, which I assume is basically the mayor—”

“that assumption is partially correct.”

So, over the course of two years, Toriel teaches me how to speak and how to use MSL. I also regain most of my memories and thus unlock powerful magics.

One day, Toriel realizes my desire to explore the rest of the Underground, so she gives me an outfit designed to resist the infection and sends me on my way with some food and water.

The forest that the door opens to is completely overrun with mushrooms. I hold out my hands, and a golden light comes out of each. The mushrooms shrivel and turn to dust once exposed to the golden light. I transfer the golden light in my left hand to my right hand and pull out a small dagger. I push forward, trailing golden sparkles behind me and preventing regrowth of the infection.

After wandering for what feels like hours, I come across… something. It looks sentient, but… it also looks infected. It doesn't seem to notice my presence, so I move on.

A few more hours of wandering, and a group of infected canines block the way.

“A human,” one growls.

“It looks tasty,” another comments.

“Where? Where's the human? It isn't moving, so I can't see it,” a third exclaims.

The smallest and largest of the dogs just bark excitedly.

I bathe my blade in golden light and slash at the dogs, making predatory grunts and growls as I do to try and scare them off. It works.

I wake up in a dark room; I have no idea where I am or even who I am. I don't remember… anything, other than my name (Frisk) and my age (15).

I stand up and search my mind.

Nothing but static.

I look around and see a path. I follow it and find myself in front of a large mushroom that looks like a flower.

“Howdy,” it says. “I'm Mushi. Mushi the mushroom flower! Say, that robe you're wearing looks familiar. You wouldn't happen to be a witch from that coven at the base of the mountain, would you?”

I give Mushi a confused look.

“No? Ok. Boy, you really are quiet. Do you even know how to talk?”

My confusion remains.

“Do you… even understand me?”

I blink a bit, my expression remaining the same.

“I'll take that as a no… In that case, there's no point in talking to you.”

Mushi disappears. I shrug and continue forward.

The next few minutes are nothing but a haze. The haze clears to reveal me sitting at a table, facing the person next to me. She notices my surprise and apologizes.

I actually understand her.

Anyway, she says, “Oh, I am terribly sorry. I did not mean to startle you. I had found you wandering aimlessly and decided to take you to my home before you became infected by the mycelium.”

I open my mouth to speak, but no sound comes out. I look at my hands, as if expecting them to do something, but nothing happens.

“Are you alright, young one?”

I shake my head.

“I am sorry, but I do not know how to help you. I am Toriel. I am the lone survivor in this area of the Underground.”

I try to tell Toriel that I don't know how to communicate, but… she doesn't understand. She only sees me growing more and more frustrated.

“Can you… not speak?”

“Ah. Nn… ugh.”

“You can speak, you just… don't know how to?”

I nod.