I wrote this as an answer to a tumblr ask I got about any left over scenes with Sans and Gaster from Project SA-N5. This was fun, if anyone happens to have more prompts like this you can send them to me on my tumblr (uncannycookie)!

There is a small, yellow scaled girl standing in his lab, staring at him through her pink rimmed glasses and shoving a doll with five long braids in his face.

Gaster, very slowly, rubs his eyes and sighs. "This is my life," he mumbles to himself.

Swiftly he straightens his shoulders and looks down at the girl (Alicia? Alberta? Something like that) with a stern expression. "Yes, hello, what do you want?"

Her lips wobble a bit, but her eyes are surprisingly harsh. "Mrs Bell lost a b-bell." When she rattles the doll, four tiny golden bells at the tips of its braids chime happily, while the fifth braid remains empty and silent.

"That is the least imaginative name I have ever heard," Gaster says. "And I live in a world where Asgore is allowed to name things. That's how underwhelming your naming skills are."

"Mean," Sans says from somewhere to the right, sounding almost delighted. He is sitting on a chair turned away from the homework table, hands jammed under his thighs and dangling his feet.

Gaster squints at him suspiciously. "You wouldn't know anything about the disappearance of Mrs Bell's fifth bell, would you?"

Sans shrugs with wide, honestly confused eyes, the very picture of innocence.

Oh, yeah, he's definitely the culprit.

Good thing that Gaster really doesn't give a shit. He quickly spins around on the spot and makes a show out of looking around, then turns back to the girl and shrugs. "Well, I tried everything. Guess Mrs Stupid-Name has to get used to life as an amputee now."

With that, he immediately turns away to get back to the important science stuff.

Gaster is haunted by Mrs Bell's bell.

And he grinds his teeth and wants to slap himself the second he thinks that, because it's stupid and unscientific and he hates it. But at the same time, he can't deny that even two days after the dumb exchange with the yellow girl, he can't get the tiny sound of a bell chiming somewhere out of his ear.

At first he thinks one of his idiots changed the alarm tone on their pager. It seems entirely plausible for them to do something like that; he should probably even be glad it's just a chime and not a kid's song or something equally annoying.

But when he throws down his instruments in the middle of an experiment, turns to glare at his assistants with a twitching eyebrow and demands that they turn that shit off, he is simply met with two very confused, very intimidated stares and one I-am-judging-you-face from Freeda.

He still makes each of them get their pager and prove to him that they haven't changed the alarm sound.

"I don't really ‒ hear anything?" Pollard says with hesitation, after they all demonstrated their alarms.

Gaster waves him off. "Well, yeah, it stopped now! Or ‒" He pauses and holds up a hand, tilting his head to the side to listen intently.

"There!" He snaps his fingers when a tiny, tiny, almost inaudible chime reaches his ears again.

They keep staring at him with blank expressions.

Gaster throws his hands up. "Well, it's very quiet. Fuck off, I'm not hallucinating!"

He's not. No matter how unsure he suddenly is about actually hearing the damn thing.

Well. It was definitely there during the last few days. But it's so quiet now, it might be he's just imagining it? Because his brain got so used to hearing the sound every few seconds?

He wipes away the thought with a quick gesture. "Whatever, why are you all standing there with your stupid pagers? Get back to work!"

Science is good, science makes him forget about the damn bell. They do their work in concentration and by the end, he's fairly certain he really was just getting a bit paranoid.

Of course, as soon as his assistants are gone and Sans returns from the adjacent room to do his homework, the chime is immediately back as well.

"What the fuck even?!" Gaster yells, kicks the unfortunate machine that's standing closest to him and rounds on Sans with hot magic burning in his eyes. "Okay, empty your pockets, right now."

Sans immediately does so, eyes wide in confusion. The only things he pulls from his pockets are a few pens, a single wrapped cracker left over from lunch and the pager for his MEC.

Gaster crouches down in front of him, pulls him off the chair and rummages through his pockets himself. There really isn't anything else in there.

For a moment, he leans forward and stares at the kid with his best intimidation-face, slowly lifting a finger to point at him. "I know you have it, buddy," he growls. "Don't play dumb with me." Then he presses the finger to his own lips, brows furrowed and his eyes just daring Sans to make any sound.

He listens. For one second, two…

… ten, eleven…

It's completely silent.

"GAH!" Gaster yells, hands scratching over his scalp as he shoots back to his feet and turns around on the spot. A cluster of tesseracts flies forth from the ground and he throws it around the lab in frustration. They take apart some unimportant equipment and one or two cupboard doors.

As soon as he calms down, shoulders heaving with his heavy breaths, he strains his ears once again.

Silence, silence, silence ‒

~chime!

"SANS!" He's on the kid in a second, lifting him off his feet and shaking him. The chiming turns into a frantic rattle and Gaster grins at him ferociously. "HA, I knew you had it! Gimme!"

Sans holds onto Gaster forearms and stares at him like a deer in the headlights. Gaster squints at him, Sans is holding his breath.

A few seconds tick by in silence again.

Then, Sans abruptly breathes in through his nose.

~chime!

For a moment, everything is frozen.

Gaster takes one deep, calm, collecting breath. "Sans," he says dryly. "Did you stick Mrs Bell's bell up your nose?"

Sans' face is quite a few shades darker than usually. Very reluctantly, he nods, squirming in Gaster's hold.

The bell chimes happily with the rhythm of his head moving up and down.

Gaster drops him to the floor, rips the glasses off his face and very strongly rubs his hands over his eyes. "How is this my fucking life?!"

It just takes a few seconds and a pair of very thin tweezers to remove the offending instrument from Sans' nose. Gaster makes sure to do it while his three idiots are there as well, because throwing the snot-coated thing in Pollard's face and yelling "DO YOU HEAR IT NOW!" is mature and justified, thankyouverymuch.

The girl (Alex? Alison? Nora?) is, for whatever reason, not very impressed with his find and refuses to take the bell back, making a few disgusted grimaces. Gaster throws it in her face too. "That's very ungrateful, young lady," he chastises her as she ducks her head squealing and hides behind Sans.

The conversation with Sans is quick and painless, as always, and done while they're rolling around the lab on another office chair.

"Why the fuck did you put it up your nose?"

Sans shrugs. "See what it feels like?"

Well. The kid does have a somewhat scientific mindset. Gaster chooses to regard the whole incident as a slightly aimless experiment.

Still, he flicks a finger against Sans' forehead and stares him down disapprovingly. "Don't put stuff in your nose."

Sans nods, looking appropriately chastised, and Gaster can at the very least count on the kid listening to him. With a both annoyed and relieved huff, he is happy to put the whole thing behind them.

A week later, Gaster curses his life and all the stupid kids in it while he fumbles a broken pencil lead out of Sans' ear.