Part 1

Boogeyman

As the record spun on the beat-up gramophone fished out and repaired from the dump, the needle scratched on its surface and produced a tune.

It wasn't one that Sans knew.

~Children have you ever met the boogeyman before?~

He hated the uncontrollable way his body shivered whenever Dr. Gaster approached him, syringe in hand. It was a natural response. He knew that, of course, but it didn't stop the shame from coursing through his body. …Not that he could usually tell when the pain started to set in. At that point there wasn't room for any emotion.

Today the needle looked different, which was only significant because he couldn't focus on much else. Longer and thinner, as the scientist laid it out on a table near where he'd strapped Sans to a chair. The bastard was humming lightly as he rifled through his medicine cabinet.

~No of course you haven't for you're much too good I'm sure~

Sometimes, depending on which lab room he was in and who else was involved, it was possible to get a few glimpses of the test sheet—read bits and pieces of the words that made sense and try to puzzle out what exactly was expected of him, or whatever process was being tested on him. But today it was out of his reach. He had nothing to do but squirm and watch Gaster work, slowly being eaten alive by anticipation.

Today was a bad day. He knew it would be. He couldn't stop the shaking.

He wanted to yell, why the fuck didn't you have everything ready before you got me out here, but the words were stuck in his teeth.

~If the boogeyman should ever come to visit you~

Whatever he was looking for wasn't there in the first cabinet he tried, and Gaster bent down to look under his sink. Completely at ease, humming in that odd, disjointed way he did. There was a bit of a clatter as he upended some beakers and pans, drowning out the next bit of lyrics and causing Sans to almost jump out of his bones.

As Gaster pulled out a small vial of clear liquid, he began to sing quietly alongside the music.

"[Hush hush hush…Here comes the boogeyman.]"

His voice didn't go along with the music—tuneless and jarring. Not that any of it was fun to listen to but hearing that voice attempt to sound melodious only made it worse. It was—creepy.

It reminded him of how sweet he'd sounded when they first faced each other, Gaster with his hands behind his back and Sans with his brother's hand in a death-grip. Talking to them like they were stray animals that needed to be carefully corralled before slapping collars on their necks.

~Don't let him get too close to you he'll catch you if he can~

After setting down the vial he produced from a bottom drawer a flask of something a dull blue. The flask was marked, but Sans didn't recognize any of the letters for its chemical composition. He didn't dare ask. As he watched, Gaster gently tipped the vial, pouring a few drops of the clear, water-like substance into the blue sludge.

There was a loud rushing in his ears and his vision briefly blacked out. That was normal for the restrained tests. Sometimes the fear would get to be too much. But he still chided himself and violently shook his head, trying to retain the anger. The anger was good. It was just hard to stay angry at things that happened so routinely.

~Say shoo shoo, and stick him with a pin~

The two fluids mixed and flared a brilliant, deep red.

"[Marvelous.]"

It didn't look right. There looked like shapes, dark shadows whirling and floating around in the bottle. He wanted to say something. Tell him that he needed to mix a different one, it looked all wrong. But it felt like his teeth were glued together. And Gaster had started joining in with the record again. He could hear that the song was skipping, perhaps because of the damage to the record.

"[Say buzz buzz, just like the wasp that stings.]"

His soft singing was even harder to listen to than the faded voice on the gramophone.

The doctor took the needle that he'd set down and carefully slipped it into the flask, drawing out the fluid. Sans began to quiver. He didn't want that inside him. He didn't want to have his bones broken off again.

"d-d-doctor g-gaster-"

A thin finger moved to lay across his mouth, silencing him. "[What have I told you about speaking out of turn, Sans?]"

Gaster didn't sound angry but could tell he was treading a thin line. "you c-can't-" It was still hard to talk. He hated it. He hated himself. "-c-concentrate when i-keep t-talking."

"[And we wouldn't want to have any…accidents while I am doing these delicate procedures, would we?]"

Sans swallowed and shook his head.

Satisfied, Gaster examined his syringe before pulling back to start up some equipment behind them-an orange light flaring up, something he didn't quite understand. "[Almost ready.]"

It didn't make him feel better.

~When the shadows of the evening creep across the sky~

He dug his clawed fingers into the arms of the chair as he was approached once more, preparing himself for the pain, the snapping of his ulna. But it didn't come.

~And your mommy comes upstairs to sing a lullaby~

The pinpricks of Sans' pupils were swallowed by darkness as Gaster went to hold the side of his face, steadying the syringe in his hand.

"[We are going to try something different today, Sans.]"

He steadied the syringe and suddenly with a sick twist inside his ribs Sans understood.

As the record skipped again, the needle pointed.

Right.

At.

His.

Eye.

"[Hush hush hush…Here comes the boogeyman.]"

He brought the needle into Sans' eyesocket like an ice pick.

Author's Note: I don't intend for this to be nearly as extensive as the Undertale Gaster fic, however I do plan to post 3 chapters on the relationship between Underfell Gaster, Sans, and Papyrus that was hinted at in my Evil Laughing fic.