[Here's a twist on Underswap AU, with some... "artistic liberties."]

Nothing seemed to work. The more they cried and howled at the pain, the worse it got. The sweets helped for a while, but the pain seemed to grow immune to its effects and returned with what felt like a sledgehammer to their head.

At best, the deafening ringing in their ears dulled so they could actually hear what their adoptive mother and loving friends said. No one wanted their new human friend to die, and Toriel wept when one day, Frisk could not get out of bed.

The pain was too much to bear.

Everyone crowded around Frisk's bed, just barely giving the child enough space to breathe. It looked like a terrible struggle, but no one could understand what they were fighting against. The child's little body writhed in pain, gripping the bedsheets until their knuckles were white; they could think of nothing else but excruciating pain. They had their eyes shut tightly, even though the darkness scared them, reminded them of a previous horrible pain, of shattered hearts, of sharp knives and ballet shoes and thorns and golden flowers and dust and-

Just when they thought they didn't need to force their eyes closed any longer, they gave in to whatever needed to be.

Anything to make the pain stop, to just end it all.

End the pain, suffering, and hell that they've endured.

And then everything went white.

.

.

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"O-Ohhhh my god! Is.. Is F-F-Frisk... D-DEAD?!" Alphys screamed as Frisk's body suddenly went limp.

"N-No way! Frisk can't die! They're not supposed to die! NGYAAAAAAAHHH!" Undyne howled. She snatched Alphys up in reflex and squeezed tightly, as if all of her loved ones were going to slip away too.

Asgore slumped down from his spot at the foot of the bed, clutching his head in his hands, whispering things of denial and guilt. "N-No... This can't be... They can't be dead... Have I done anything wrong...?"

Sans was silent. He had Papyrus leave the room after promising that Frisk would be alright. He wasn't so sure if he could keep that promise.

Toriel said nothing and rushed to put an ear against Frisk's chest, desperately searching for a heartbeat. She tested their neck and their wrist, in denial and no, no, not ready to lose yet another child, not this one, please...

She was just about to give up when she sensed a weak pulse in their neck, and tears of joy instead of grief ran down her face.

"They're... They're alive... Unconscious, but alive..."

As everyone absorbed those words and broke down in tears, Toriel immediately began using healing magic, hoping and praying for the best.

Her healing abilities only go so far as physical injuries, so she couldn't do anything to wake Frisk up. It was the most she could do to keep her child alive, and she didn't want to waste any precious time driving to the hospital, even if the doctors could help better than she could. She could sense their weak heartbeat strengthening with every minute that went by, and she was eternally grateful for the gods that smiled upon her and her family.

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.

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She could have let go by now, stopped using her powers, to just let the child sleep in peace, but she didn't want to. What could happen? She didn't dare find out. Even though her powers were draining away, healing whatever it could, she didn't dare pull her hands away. As far as anyone knew, she became Frisk's lifeline, the tether so Frisk's SOUL would stay on Earth. No one wanted to distract her, so they quietly took their leave.

She was alone with Frisk, but not quite.

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Several hours went by, and Frisk finally came to. But only after someone else somehow brought them to the kitchen and opened the fridge, a cold bar of chocolate gripped in their hand as their other one shut the door and their feet walked to their bedroom.

They didn't do that.

They didn't do any of that.

No one else seemed to be in the house, either, aside from Toriel's quiet snoring in their room.

My room.

"It's good to be alive again. I have to admit, being dead wasn't that fun," a voice-that was-not-their-voice said. "Where is everyone? Hopefully they're buying chocolate." Positive senses and receptors in their brain were fired, but they were out of Frisk's control. If anything, their brain should be screaming fear.

Who was this?!

"Hm? Don't you know who I am? You've met me before, partner. You wound me..."

...Ch-Chara?

"The one that comes when people call its name. That's right."

Adrenaline pumped through their veins as Frisk's body suddenly bolted to the bathroom of the house, completely out of their control. Looking into the mirror, Frisk's -no, they're Chara's now- eyes opened to reveal blood red irises plastered onto their face with a terrifying grin.

"It's me, Chara."

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((A/N: Gsviv'h z mvd hsviruu rm gldm, zmw gsvb kozm lm hgzbrmt.))