-in this prolague, *** means switch writers, and ~~~ either means somewhere else or time skip, also all art belongs to me please don't steal it-
(First section is mine)

Magenta was just wandering around the multiverse, when she saw fresh getting a new body, perfect~ this was the best possible opportunity to test out her new prank kit. Magenta checked the codes to try and predict where fresh would be next.
'got him'
Next stop Underswap #72
She went before fresh got there and set up her prank. Magenta took a small container from her prank kit. Written in small, fancy, cursive, was the message: Magenta's sneezing powder. Don't touch.
Taking a water spray bottle from here kit, Magenta unscrewed the top, and put in, with the water, a quarter of the powder that was left in the bottle.
The skeleton watched and waited for her target to come from a portal, so that she could get the jump on him.
**************
Ink scowled as the AUs flew by. He was in the middle of fighting Error when Nightmare showed up. The two didn't even hesitate before attacking at the same time, forcing Ink to run. Eventually he stopped at an Underswap AU and turned around, facing the dark skeletons before him. Wasting no time with words, Ink twirled his brush, ready to fight when it happened. The first thing he noticed was a spray of water hitting him in the side of his skull, followed by a familiar voice yelling "GOT'CHA". The next was Fresh beside him jumping back, before laughing loudly. The third thing he noticed, as he stared blankly at the startled skeletons he should've been fighting, was a tickling sensation spreading across his face.
Oh
Oh no
Ink doubled over, covering his face with his arm, and sneezed hard. Ink poured everywhere from out of his face. His eyes, nasal cavity, and mouth was filled with the dark substance as it spread across the ground, much to the disgust of everyone else.
"Ugh Ink! Clean that shit up, nobody wants to see that nasty black stuff everywhere." Nightmare scoffed. Error snickered before turning to his partner.
"Then why are you still here?" Error started cackling as Nightmare backhanded his skull, trying not to looked amused. Ink opened his mouth to yell at the squabbling pair, when he sneezed again.
And again.
And again.
"Why-"
Sneeze
"Am-"
Sneeze
"I sneezing-"
Sneeze
"So much?!"
Everyone backed away from the sneezing skeleton before turning to the only person holding a spray bottle. Unfortunately, Ink saw her before she could get away.
"Y o u"
Not giving the monster a chance to defend herself, Ink attacked with a sneeze of rage.
*************
"Ahh shizz!!" Magenta shouted (censoring herself), bairly dodging the ink spued at her. Magenta turned herself invisible and quickly teleported behind ink, and with summoning a bone attack, hit him upside the head.
Ink, not ready for the attack rolled forward, and had to catch himself. After another sneezing fit, ink stood up with his brush at the ready, and tried to hit Magenta again, and again, and again, never being able to hit her. Magenta had dodged all of inks attacks, as she was faster than the slightly disoriented, paint brush welding skeleton.
She was getting tired, even as a sans she seemed to be even more lazy then the original, or maybe it was a ruse, either way she was tired right now, and it was beginning to show.

Ink was getting closer, and closer with every swipe of his brush, to hitting the female prankster. Finally Magenta teleported a few feet away, and, summoning her bright magenta strings, trapped the artist for a few moments. In those precious moments, Magenta looked over to Nightmare and Error, who had somehow gotten their hands on a bag of popcorn.
"ummm... help please? He's your enemy."
Magenta asked, scowling at them with what little power she had left.
"naw" Nightmare said in between bites of popcorn "you've got this". Magenta rolled her eyes and turned her attention back to the artist just in time for her magical strings to run out. Ink was in her face in seconds with another attack,luckily she was able to dodge again. Magenta then heard Fresh's voice over the commotion.
"welp my radical homeslice gal, betta luck next time! But now I gotta skedaddle" Magenta turned to look at fresh, only to see him fleeing through a colorful portal.
'this is perfect' Ink thought, raising his brush, he hit Magenta on the head, cracking her skull.
"shit!!" Nightmare said before her world went dark and she fell through her portal.
*************
Ink growled, seeing his target fall through a portal. As he doubled over to sneeze again, tentacles and blue strings wrapped around him, bringing Ink gave to face with two very angry skeletons. Waves of negativity and destruction crashed over Ink as the two regarded their prey. Nightmare and Error stared at each other, having a conversation with their eyes.
Nightmare: we should grind him into dust
Error: he'll just turn into paint
N: so???
E: I don't wanna get it on my clothes...plus we gotta check on Magenta
N:shit you're right
E: I'm always right
Error struck an arrogant pose as Nightmare snickered next to him. Not knowing nor caring what was going on, Ink swept through his bonds with his paintbrush and left, searching for Magenta. Ink has had enough of her pranks. Sure some were funny, but she keeps getting in his way. If Ink could only get his hands on her, not only would she be out of the way, but he could use her against the dark Sans that keep messing with the AUs! Maybe he could even get her to join him! He has to get her back.

Error and Nightmare exchanges worried looks. They knew how obsessive Ink could get, if he got his hands on Magenta, who knows what he'll do to her. Luckily the two knew where she was. A few years ago, the trio had established a connection between their magic systems, allowing them to find each other anywhere.

Opening a portal, Error and Nightmare stepped out into waterfall from underfell 58.

(This is what she looks like now)

Laying in the grass was Magenta, a large crack running down from the center of her forehead, all the way down to her nasal cavity.
"MAGENTA" the two shouted as they ran to her side, Nightmare already activating his healing magic while Error stole some healing items from various AUs. As the female skeleton slowly woke up, both of them were asking questions rapidly.
"Are you ok
"Does anything hurt?"
"How many tentacles am I holding up?"
"Do you remember us?"
Error, destroyer of worlds, and Nightmare, king of negativity, were fawning over someone like doting parents. If anyone were to see this they'd faint, then believe all to be some strange dream.
************
"mhhh...... I don't feel good" Magenta said, her voice slightly horse.
"and my skull hurts...what happened?" she lifted her fingerless gloved hands to her skull to touch what hurt, but error grabbed her wrist lightly before she could feel the crack.
"you were attacked by ink... here eat this" Error told her, handing Magenta a healing magic rich food he had stolen.

It hadn't always been like this, them being nice. When Magenta had first appeared, nightmare and error attacked with all they had, thinking she was with ink. After that however, the couple took her in, as she was just a kid. They got her food, drink, shelter, and clothing. It always seemed as if she liked pranking people, so for her 13th birthday, Error and Nightmare introduced her to Fresh. Fresh had been a huge influence on the the young skeleton, for example, he taught her how to censor herself, how to prank people in the most effective way, they even started a prank war, then again that was the reason they were even in this situation. Even when Magenta first met him, she had hated ink. He hurt the people who cared the most about her! They never got along, and even fought sometimes, but Magenta didn't really care about Dream and core frisk, although they were always fun to prank.
That brings us to now, where the 15 year old skeleton was lying on the ground, tired, hungry, and magic deprived.
Magenta looked from side to side, seeing her reflection on the rocks. Her magenta tinted bones were dirtied and scratched, the circle of magenta in between her sockets looked no better, and her eyelights were dim.
She was wearing a neon green shirt with darker green frills lining the neck and shoulders. Now, however they were tattered, not protecting her from the chill in the air. Her prank kit (an old brown bag) was ripped as well, she would have to find a new container for all her items. Luckily her dark purple shorts and fingerless gloves looked fine and unscathed. Which was good because she had Error teach her to make them.
All in all she was a mess.
"dunkle Nightmare?" she said straining to keep awake. "mhh" he hummed in acknowledgement before continuing to heal her crack. "I'm going to take a nap" Magenta finally said before once again she drifted into unconsciousness.
*************
Error started to panic. "No nonono don't fall asleep! Magenta!" He reaches for her shoulders, intending on shaking her awake. Nightmare uses his tentacles to hold Error beside him and away from Magenta, not looking away from the wound he's healing.

"You're going to hurt her." He murmured. "Let her sleep, I'll make sure she wakes up ok." Error sighed, leaning his head on Nightmare's shoulder.
"What are we gonna do with her? If Ink finds her again..." he trailed off, eyelights never leaving Magenta's still form. Nightmare hummed, choosing not to answer his worried lover. Having Error worried gave him more strength to maintain his healing magic, which was never as strong as his brother's. Not long after, Nightmare slumped onto Error with a sigh, feeling drained from all the magic he used. The crack was still there, but it shrunk, now it went from the center of her forehead just barely past the top of her eye sockets. If she really wanted to, Magenta could easily cover it up with some magic. Error poked the tired monster currently flopped over on him.
"Heyyyyyyy" he complained, "get off ya lazy sack of goo." Nightmare's response was to simply groan and shift, this time putting all of his weight on Error. Muffled curses could be heard from the pile as Error struggled and Nightmare fell asleep.
****************
Magenta woke up a few hours later. She looked over to see Error napping underneath a sleeping pile of inky octopus that was named Nightmare. She sat up and scooched over to the skeletons,when she got there she felt tired so Magenta leaned onto Error and fell asleep again.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Error woke the next morning with Nightmare on top of him and Magenta sleeping on his side. After pushing nightmare off of him - earning him a death glare - Error shook Magenta waking her up.
"mornin dunkle Error~wassup?" Magenta said playfully and groggily after waking up.
"nightmare finished healing you last night, you really have to stop pushing yourself like that." Error replied, pointing to the now once again sleeping form of nightmare.
"there's a scar, but it's small enough to be covered with magic" he said, now pointing to the scar. Magenta looked to one of the waterfalls to see her reflection.There, going from her forehead down a little past the top of her sockets was a jagged,deep, but light scar. Instantly, Magenta decided to cover it. She hated looking hurt, it just made people worry more than they had to.
After thanking Nightmare and Error for healing her, Magenta had to go, she had planned to hang out with Fresh for a few days and she was already late.
After Magenta left, Error turned to Nightmare.
" She can't keep getting hurt, we need a better way to protect her. You saw the look on inks face, we need to find a good place for a teenager like her to grow up." Error said, distraught.
"I know babe, I know." Nightmare reassured hugging his mate close.
~~~~~~~~~~~~~~~~~~~~~~~~
Ink had gotten dream, and they looked through AU after AU looking for Magenta, to no avail. Then suddenly they felt the distinct magic of one of her portals opening and closing. Ink teleported to the AU she was in, keeping out of sight, while dream teleported on the other side of her, also out sight.
********
Ink watched as Magenta stretched, looking oblivious to the area around her. Signing to Dream, the two slowly crept forwards. Ink saw their target tense and knew he had to act now. Exchanging nods with Dream, The pair lunged, tackling Magenta to the ground, quickly knocking her out and putting a magic-suppressing collar on her. Dream shifted, looking guilty at the unconscious form. "I don't know Ink, are you sure this is right?" Ink was quick to reassure him. "I know we had to be a bit rough with her but this is for the best! Now she won't fight us while we help her. You've seen how easily Nightmare manipulates those around him, if we act fast we can still save her from him." Dream nodded, looking appeased. Ink relaxed, he almost felt bad for lying to the other but what else was he supposed to do? The guardian of positivity would never capture Magenta if he thought she was happy with Nightmare. It was easier for everyone this way. The two grabbed Magenta before disappearing into a portal.

Elsewhere Error froze, terror flooding his system. Nightmare looked down, concerned for the smaller skeleton.
"Error? What's wro-"
"She's gone" Error started to cry. "I can't sense her magic any more." Nightmare tensed, every part of him screaming in denile.
"Ink has Magenta."
**************
Magenta felt weird, and not the good kind of weird.
She tried to open her eyes, but there was a tight piece of fabric keeping them closed.
She tried to lift her hands to remove the fabric, but as soon as she got half way, they wouldn't go up anymore. Magenta felt metal around her wrist, and heard the surefire sound of chains clanking behind her.
Where is she?
~~~~~~~~~~
The two grabbed Magenta and before disappearing into a portal. When they got to the other side, Dream went and got a blindfold, while Ink lay Magenta on a bed. When Dream came back to the room, Magenta's wrists were secured to the bed posts.
"are you sure we have to chain her up?" Dream asked, still unsure about the plan. Once again Ink was quick to reassure him.
" Yes I'm sure, if we didn't, she would leave and we wouldn't be able to help her. Nightmare could get her again". That seemed to have pacified Dream, so the two gardiens made a plan. Today dream would watch Magenta while Ink tended to the multiverse, then tomorrow Ink would watch her. Once they were done planning, Ink tied the blindfold around Magenta's skull, and took his leave. Now all Dream had to do was sit down and wait for the smaller skelegirl to wake up.
~~~~~~~~~~~
Elsewhere, Nightmare and Error were beginning to freak out. Where had Magenta gone? Without her magic online they couldn't just instantly find her and protect her. So the two decided to get fresh, then split up and such the whole multiverse for there friend/kid (nightmare and error where like adopted parents they raised her from the young age of 4).
~~~~~~~~~~
Dream watched as Magenta started to stir, taking a few moments to what seemed to be trying to her eyes and lift her hands.
"Heya! Good morning Magenta!" Dream said enthusiastically, getting the attention of the female, making her head turn to him.
"who are you?! What did you do to me?! And can you please take of this god forsaken blindfold? !?!?!" she said very angrily. Dream was slightly taken back from the tone of her voice, before getting up and walking over to her. As Dream took off the blindfold he noticed a healed over scar that went from her forehead to her sockets. Why hadn't he seen that before? He asked himself before deciding to ask her later. Must've been Nightmare.
"There, is that better?" dream asked Magenta calmly.
"should've known that it was one of inks lackeys who did this." she spat out the words like poison.
"but yes this is soooo much better. It's not like I was knocked out and kidnapped when I was just going to see fresh." Magenta finished, every word with a growl and a bite to it.
***********
Dreams eyes widened at her words. "W-well when you put it that way...it sounds pretty bad but." Dream brightened up. "It's ok now! We took you away from Nightmare, so he can't find you anymore." Magenta growled. "I never wanted to leave him you dumb funk! He's never hurt me, unlike you and Ink." Dream took a step back, horrified. "Oh. Oh no" he whispered. Magenta looked triumphant starting to grin.
"I'm so sorry, this is so much worse than I thought."
Magenta smirked. "See? I told yo-"
"You have Stockholm syndrome"
... Magenta facepalmed. Dream was trying to hug her, much to her displeasure, while crying that it was going to be ok and they'll fix this somehow.