Work Header

The Exorcise World (of Monsters and Witches)

Chapter Text

I don't own Underfell, Undertale, or Underswap. Frisk is female her, sorry, I'm not very good at they/them pronouns.

Warning Please Read: there are some parts that mention blood or some gory chapters, while it may only be mild, I'll do my best to put a trigger warning or a warning. Please skip if you need to.

Pairings are: Everyone/Frisk. I've had a recent obsession with this pairing, unfortunately or fortunately.

Also, the ages are the following: note, these may change.
Frisk- 19
Classic Sans- 21
Papyrus- 19
Honey (US paps)- 21
Blue- 19
Edge (UF Pap)- 19
Red- 21
Note: monsters here don't really care much for ages, so this will be really minor in the story. If you want, just imagine frisk being 18 or any legal age with the skeletons. These are only my hc's of their ages in this au, and even then it's really flexible.

By the way, their still wearing the same clothes from their respected AU's until stated otherwise.
And I'm so sorry if I got something's wrong here, I did not mean to offend anyone!

Long ago...

there was a tragic war between the Witches and Monsters. The reason at the time were unknown, only to the fact we Witches feared the power we did not have.

Despite this, Witches overpowered the Monsters in power so much that it could not be called a war at all but instead a massacre.

The battlefield they fought in was covered in dust. The remaining Monsters, tired and weary, knew they lose and mourned for the death of their dear friends.

And so, the Monsters surrendered.

The Head Witch had plans for the Monsters, the Leader at the time hated the war and did not agree to the ideals of the former Leader. Also knowing that if they were to banish them or to kill them, they would lose a great ally, had devised a plan– a treaty.

A day after the surrender of the Monsters, the Head Witch proposed the idea of a treaty, a union between the two races.

Kindhearted was the King and Queen of Monsters, did not want to bring forth another war, knowing they would once again lose, agreed to this treaty. This decision was also helped to the fact that they knew the Head Witch of that time, was a kindhearted and loyal one and would never betray them.

To this day, the treaty brought great things to them.

And that, is now.

Welcome, to a world of Exorcise.


"Everyone! Evacuate to the upper levels, right NOW!" Yelled Frisk, the top student and assistant of the headmistress as she ran towards where the chaos was.

Right now, the Exorcise Academy was in chaos.

The normally clean hallway was covered in dust and debris, rubles were everywhere, but luckily, no one was dead and only minor injuries were made.

Students were running towards the upper level where the safe room was, the barriers were strongest there, it was expected as the headmistress was the one who had cast it.

"Teachers guide the students! Exorcise create barriers!" She shouted once more, using her magic to amplify her voice.

Doing as told, the Professors tried their hardest to escort them to their safety, casting barriers left and right, up and down.

"Frisk! We gathered all the students and Professors. All we need is to gather to Room 1." An Exorcise said, running towards Frisk, he's voice trying to remain calm.

Frisk nodded, "Good, now hurry and catch up to them. Help as much as you could, but be careful, the Poltergeist is strong, it's Magic may reach us here. I'll go and stop it, and purify it if I can." Getting ready, she tried to pinpoint the dark tendrils.

"Wha-what?! But it's a Level 4! You could get seriously hurt or die!" His composure faltered, as he told her, stuttering and eyes wide in disbelief.

Smirking, Frisk adjusted her gloves, her normally closed eyes opened. "Have you forgotten who I'am? It's my duty to protect this Academy and it's people. That includes you."

Seeing his reluctance to leave her, Frisk eyes softened. "If it helps, I'll be extra careful."

Sighing, he nodded in defeat. "Fine, be careful." With that he followed the remaining Professors.

Frisk watched for a moment as the Exorcise that were hired did as was told, casting barriers and shield where the teachers cannot reach, before moving where the center of the chaos was.

it was luck that the cause of the chaos happening had not yet reach the third level, the level they were right now.

Though maybe it helped there was a strong shield and barrier placed there by Frisk.

Nevertheless, they were very lucky it had not reached them yet.


Running towards the lower level, where the level 4 poltergeist was at, Frisk got ready for the fight that would happen.

She was very glad she had put the barrier as soon as she felt the black aura. Luckily, there had not that many damages as she has expected, only rubbles and debris, those are easily fixed with magic. Loss lives are not.

Shaking her head, she cleared her thoughts, sharply turning to the corner where she felt the aura, and prepared for the battle.


In front of her was a big room that was once used for training young aspiring exorcist, what was once clean is now full of rubbles, debris, dust. In the middle of the mess is the poltergeist, the floating form was that of a young girl wearing a dress soaked with blood, pale white skin, the face was bloody, pitch black eyes with tears of blood running down her cheeks, mouth pulled into a creepy smile. She was covered with black aura– a sign of hatred. The aura was curling around her like tendrils, lazily floating.

That is, until she caught sight of Frisk standing at the doorway.

Frisk was wearing a plain brown shirt, and a long white coat that reached her knees, the back was with the insignia of the Exorcist Academy she wore proudly, her shoulder had the crest of Witches, she wore shorts with black stocking, and her shoes were boots that also reached her knees. Hair down, her gloved hands were holding a scythe and her red magic was floating around her, prepared to comply to her wishes.

"Hello there, I'm sorry but I have to ask you to leave. You have caused enough problems here, I could help you move on if you would allow me too." Frisk said kindly, opening her arms to show she would not harm the child.

Moving forward slowly, as to not startle her, she vanquish the scythe with a soft red glow, as to show she was not lying. However, the poltergeist did the opposite, sending the tendrils towards her in high speed with a lift of an arm.

Moving left, Frisk dodged it easily. "Now, now, please stop. I only wish to help you, I don't intend to hurt you. I promise." She said calmly.

"NO! tHeY aLL Said tHaT buT tHEy sTiLL HuRt mE!" The poltergeist child roared at her, the voice was static and disfigured, her Hate giving her the power to push Frisk back with great force.

Using her Magic, Frisk coated herself and floated the moment she touched the wall. Frisk was confused to who hurt her, but she was also angry at them for hurting the child.

Touching the ground she prepared her magic, "I promise, I will not hurt you. I only wish to help you!"

More black tendrils charged at her from everywhere, knowing there's no dodging that, using her Magic she casted a shield.

««Protect!»» A red dome made out of Magic was suddenly over Frisk, and the moment the tendrils touched the red Magic, the tendrils all disappeared with a red glow.

As soon as the tendrils were gone, the red dome also disappeared, having done its purpose.

"I'm not like them!" Frisk repeated, trying to get to the child, "I promise you! I won't hurt you!"

"StOp lying!" The child howled at her, the amount of Hate grew until it leaked at her everywhere, trying to get out, the voice was getting more and more static, most of all was that her form was glitching that Frisk was worried it would all explode if she didn't purify the poltergeist child soon.

"I really didn't want to do this, I'm sorry." Frisk said under her breath. Louder she told the child, "I'm sorry, it looks like I'll have to do this the hard way."

Frisk went into a defensive stance, legs crouched, feet separated, and hands both holding her red scythe. Her  face was set in a determined expression. Frisk was Determined to save the child, and that determination only fueled her Magic.

I'm sorry, Frisk thought. Then, she started. Concentrating her Magic on her back, big wings sprouted, as she flapped her wings, a huge gust of wind were created.

"What ArE yOU Doing?!" The child growled at Frisk, her body tensed into a defensive stance of her own, her claws are barred, mouth in a snarl, feet floating, the black Magic was cautious, aggressive and tense, the tendrils were prepared, and ready to attack in any moment.

Taking a deep breath, Frisk said. "Trying to help you. I'm sorry for those who hurt you before, but I promise you, I'm not like them. I will never hurt you. Not if I can help it." Floating high on the ground, her form changed slightly her scythe was longer, her normally gold eyes glowed, and her hair changed to the color of silver. All of the sudden she looked like an Angel.

Feeling fear, the child was desperate to attack, charging at Frisk with her tendrils and the black matter, her form once again glitched and her black Magic was rampaging to get out of her small body.

I'll need to do this fast or it'll be to late. Frisk though as she charged as well. Hair flowing, face in a determined expression, her wings flew.

Knowing there's hope in saving the young poltergeist gives Frisk DETERMINATION.

Upper Level: Room 1 [Safe Room]

Third POV.

"Anyone who need medical attention, please move towards the Healers immediately! Helpers are appreciated! Those who are not majorly injured, and those who still have enough Magic, please help those in need!" A professor said, amplifying her voice to make it louder. The professor was standing in the middle of the room, giving instructions and help to whoever needed it. "Those who have little Magic or half full, please go to the Healers immediately!"

Currently in the Room 1 [Safe Room] everyone was worried and tired, the professors, Healers, and Exorcise were trying their hardest to help the students that were injured or needed to replenish their Magic. Running around in a frenzy, they too were tired, the students, not wanting to be helpless and be useless also tried to help the best that they could. The rest were too exhausted to help and simply wanted to sleep and rest.

It was a sudden glow that caught everyone's attention, stopping some from their activities.

Everyone was surprised when it was the source came from the gold «Teleportation circle» that was painted on the floor from the right corner of the room. They were even more surprised by the guest stepping out of the circle.

"SANS! ARE YOU SURE WE ARE IN THE RIGHT PLACE? THIS DOES NOT SEEM LIKE THE ROOM WE SAW IN THE TELEPATHY GIVEN TO US." A loud voice asked, as owner of the voice stepped out of the circle. It was not what the students expected, instead of a normal Witch or Monster, it was unlike anything they have ever seen. Some goggled at them, some raised eyebrows, while some just shook their head. It was normal to expect the unknown.

It was a Skeleton, and it seemed to be more than one.

While the students did not expect it, the teachers seemed to have, for their eyes had widened in realization. Before they could say anything, however, they were interrupted by a deep voice lazily speaking.

"pretty sure, paps. i mean, we're not the only ones here, see? they fit the uniform of the academy. besides, it's not possible for the teleportation to be wrong. the magic we used was strong enough to shield us from any interruptions." The voice came from a short Skeleton Monster wearing a blue hoodie, hands in the pockets, and pink sleepers coming out of the circle with a lazy smile. Following him were four other Skeleton Monsters.

Facing them, Sans– deep voice, short in height, blue hoodie– greeted them, "yo, nice to meet you, I'm sans. and this here," Gesturing towards the first Skeleton who spoke, "is papyrus, my bro."


"AND I'AM THE MAGNIFICENT BLUE! THIS HERE BESIDES ME IS MY BROTHER, HONEY! IT IS ALSO PLEASURE TO MEET YOU!" A small Skeleton loudly said, the height was about a head taller than Sans, pointing at his right was his brother, Honey, who lazily raised a hand to wave.

"yo. nice to meet you." Honeys height was at the shoulder of Papyrus, which was impressive considering how tall Papyrus was.

"HMPH! I'AM THE GREAT AND TERRIBLE FELL, BE HONORED TO STAND IN MY PRESENCE!" Another loud Skeleton said to them, Fell had the height of Papyrus, wearing combat boots and had the same scarf as Papyrus has. His face was with a scowl and looked quite unhappy being here.

"RED! INTRODUCE YOURSELF! IT'S BEST WE GET THIS OVER WITH." His voice was directed towards another short skeleton, that was the height of his Fells waist. The skeletons posture was slouched and his digits inside his black and red hoodie pockets.

Red seemed to wince at the shout, rubbing his ear sockets, his skull sweating a bit (how is this possible?). Reds smile seemed to strain a little, finally he said. "geez boss, no need to shout."

Fell seemed to twitch at this, but before he got to, most likely, shout his response, Red continued, raising his hand in a lazy wave, much like Honeys, "yo, nice to meet ya, I guess. names red."

Wiggling his brows (how?) in a flirty like way, he seemed to aim his lecherous smile towards the females, "and I would love to get to know you more,"

Some of the female teachers blushed, as well as some senior Exorcise. And a certain teacher was sure they heard a giggle as well.

"ENOUGH! STOP THIS NONSENSE IMMEDIATELY OR I WILL MAKE YOU!" Fell lectured him, scowling at Red heavily, he put his arms towards his waist, "WE ARE NOT HERE TO PLAY, WE ARE HERE TO HELP THEM AS ASSISTANTS. REMEMBER THAT RED!" Fell leaned towards him as to show his point.

Putting his hands in a surrender position, Red tried to placate Fell, sweating heavily and putting a nervous smile, "right, sorry boss. i'll remember that next time. won't do it again." Hearing a snicker behind him, he looked behind to see Sans, and Honey smirking with a smug look. Glaring at them, opening his mouth to say some vulgar things, but before he can say them, he was interrupted by Papyrus voicing out his concerns.

"HUMANS! WHILE I'AM VERY HAPPY TO MEET YOU ALL, I'AM VERY CONCERNED ABOUT HOW WE CAME TO THIS UNFAMILIAR ROOM. THIS ROOM LOOKS NOTHING LIKE HOW MADAM TORIEL GAVE!" His face was pulled into a concerned expression, mouth in a worried frown, and eye sockets looked concerned.

"THAT'S RIGHT! DID SOMETHING HAPPEN? THIS ROOM LOOKS LIKE IT SHOULD ONLY BE USED IN EMERGENCIES!" Blue hopped in, his face also giving a concerned and worried look.

The both were right. The room is only used in emergencies. The surroundings were covered in supplies like first aid kits, and dry foods. The wallpaper was grey and white, there were multiple rooms that covered every students needs like toiletries and beds. The room itself was large, it was like a ballroom, with its size big enough to cover everyone from the academy and more. The ceiling was painted with the symbol of the Academy and Witches. A bright yellow star.

The students, Exorcise, and teachers exchanged uneasy looks. It did not go unnoticed by the Skeletons, they felt uneasy, when they first came out and looked around, they were were wondering why all the students and staff were looking so ragged and injured.

As far as they knew, the only way you get transferred in a different location intended was when the Receiver changed it at will, or there was an emergency and the «Transportation circle» was changed to suit its masters needs.

"Umm, well..." a Professor stuttered, her brown ponytail hair was frizzy with stress and worry, her face was covered in minor cuts and her normally pristine uniform was torn and dirty from dust that came from the debris and rubles (here Sans, Honey, and Red were relieved), her brown eyes looked tired and her Magic seemed almost depleted, but not so much she would need medical attention.

"Professor Lim, it's okay, we'll handle this. You go get some rest." A tall man said, taking her place and gently guiding her to the medic place so that she would get some sleep. It seemed that tall man talked to the medic about something before coming back to speak to them.

"I'm sorry, you must be the assistant professors that were sent to come here. I'm Adrian, a professor here for Magical Biology." Adrian said, he looked like the age if 20's, his height was that of a tall man with short hair–which was in disarray– his uniform was, like everyone else, in tatters and dirty. His face was dusty and scratched in some parts. Adrian's black eyes were tired and worried. Unlike the lady –Professor Lim's Magic, his seems only half full, which was a good amount enough to restore again.

Still, he smiled at them, hoping to welcome them the best he could in this situation.

"I wish we could have met in a better setting, but this happened. I'm terribly sorry for that." Adrian gave them an apologetic look, looking genuinely sorry, his mouth pulled in a grimace.

"IT IS FINE, HUMAN! I, HOWEVER AM GREATLY CONCERNED AND WISH TO ASK WHAT HAPPENED TO EVERYONE! YOU ALL DON'T SEEM TO BE IN GOOD SHAPE!" Papyrus asked, standing in front of Adrien, with his height he easily towered over Adrien, but instead of feeling threatened, Adrien excluded calmness.

At the question, though, he sighed and scratched his hair, a habit he did when he was feeling anxious and worried.

"Well, you see..." He started explaining, "We got attacked by a Level 4 poltergeist..."


Frisk wondered what this place represented, like all the other rooms.

"Let's see here..." Frisk said, looking around at her dark surroundings. Still in her new form, Frisk was currently in the mind of the poltergeist– Anna, Frisk found out in a room when she looked through around her mind.

As her eyes adjusted to the darkness, Frisk examined the surroundings closely, the walls were grey and the floor was wood and were creaking in some parts. The ceilings were dark and had some liquid dripping down, making a 'drip drop' sound. She was in a hallway, her mind supplied. A very dirty hallway, too. The surroundings were covered in garbage bags, and there were some rappers and empty bottle cans that collected bugs and cockroaches.

The Hate was strong here, covering the entire hallway, she wondered why, and felt cold.

Frisk swallowed and continued. Determination coursed through her, no matter the reason was, Frisk would help her.

At the end of the hallway, she found a door.





And thats a wrap! Thank you all for reading all this, sorry this was all so long, I promise the next chap would be... shorter? I  think, eh i'll decide it when I write it.

For an explanation: In this au, that I made, there are Witches and the supernatural (ghost, spirits, etc.). The Monsters surrendered and was given a peace treaty by the late leader of the witch. The 3 aus are here caused by a Void experiment, which will be explained later. or on a chap. While there are humans here, they are not the strong ones, in fact their the opposite, the Witches are the ones who attacked the monsters and won, but instead of the Monsters running to Mt. Ebott, they were given a chance by a witch, hence the treaty.

If you have a question, don't hesitate to ask, i'll answer as soon as I can.