“HEY FUCKER! OPEN THIS GODDAMN DOOR!”
The sudden pounding had several effects.
Babybones jumped, limbs twitching suddenly as blank sockets opened wide in shock.
Sans flinched and then growled lowly as the panic from Babybones echoed into his soul.
Papyrus rolled his eyes.
“I’ll Get That.” He sighed, standing from where he had been sitting at the counter with Sans, Babybones propped up in a circle pillow on the counter while they had been eating dinner. He had been working on his volume while around Babybones, at least until her eyelights came in. While she could (apparently) sense his magic enough to know when he entered the room, she still couldn’t get a good read on where he was, and the times he had talked at his usual level had startled her.
Sans groaned from his soul, already knowing what was to come. If Undyne was here, Alphys likely was too, and if they were both here without warning then they didn't--
"YOU MISSED PRACTICE TWO DAYS IN A ROW! WHAT THE FUCK IS WRONG WITH YOU?"
A (relatively) quiet mumble answered while Sans tried to calm the still-panicking Babybones. Loud noises, unfamiliar magic, her panic was echoing in his chest and making him grit his teeth hard enough to grind. It was Undyne, his Bros bro, he was not going to attack her, he was not--
"The Fuck Do You Mean, Lower My Voice?! Why Do-" The only slightly quieter complaint was cut off with a choke like she had tried to inhale and swallow simultaneously.
Sans turned towards the open arch of the kitchen, trying to send waves of calm he did not actually feel toward the Babybones. Under the arch, Undyne was bent over, hands on her knees as she coughed, yellow eye wide and still locked on the baby.
"B-babe? What-" The loud gasp followed by a squeal was pretty much what he had expected. "OH MY STARS, SHES SO CUTE!"
That...was officially the loudest he had ever heard Alphys get in the long time they had known each other. It was kind of impressive.
Except for the way her sudden shriek startled the baby badly enough that her face scrunched up as she began crying, arms immediately reaching out in search of him.
The growl he let out was involuntary but echoed in the room. Alphys squeaked, hiding behind Undyne who glared at him but didn’t snap at him. He pulled back the sound as much as he could, though a subvocal sound stayed.
Reaching out he picked up the little one, cuddling her close.
“What. The. Fuck.” Undyne asked, careful to keep her voice low. Sans ignored her, focused on holding the tiny Babybones close, sending calming vibes to her through his soul. She slowly calmed, small whimpers trailing off into quiet breathing as she grabbed onto his shirt.
“As You Can See, I Had A Reason For Calling In,” Papyrus states, pushing Undyne to the side so he can get back into the kitchen. "If You'd Like, There Is Plenty Of Dinner." He offers, settling back into his chair. He gently brushes a tiny cheek with a single finger, Babybones twitching at the touch but grinning at the familiar magic.
“What. The fuck.” Undyne repeated, seemingly frozen in place. Alphys was damn near vibrating in place, both hands clamped over her mouth. Sans sighed.
“she’s mine.” He said shortly, stroking Babybone's skull with his thumb, soothing her. She calmed completely, turning her face toward the unfamiliar magic and noise, curiosity peeking through.
Alphys made a noise similar to a tea kettle.
Undyne patted Alphys’ head absently, pulling her back from the edge of excitement. They both took a deep breath in sync, letting it out slowly.
“How- What- Why-” Undyne stuttered.
Sans sighed again.
“I went through my heat and had an…accident.” He admitted roughly, not liking having to say it like that but not knowing how else to do it. If any other monster asked it would be met with a short “nunya” but this was Undyne and Alphys. They were practically family anyway.
“An ‘Accident’.” Papyrus mocked under his breath, earning a sharp smack upside the head from Sans. He growled a little in response to the hit, but quieted down when Babybones whimpered again. Once more he reached out a single clawed phalange and gently drew the back of it against Babybones cheek.
“An a-accident?!” Alphys squeaked, a slightly mad look entering her eyes. Sans glared at her, and the mad look immediately rescinded, Alphys looking apologetic. “H-how?” She asked much softer, leaning forward a little to try to get a better look. Undyne appeared to be in a state of shock, mouth hanging open a little.
Sans felt himself blush, the two visitors clocking it immediately, brows raising. Papyrus laughed quietly, reaching out to take Babybones from Sans now that she had calmed. With care, he leaned her back onto the pillow, making certain her head was propped up. Hands now free, Sans found himself fidgeting in place, scratching the back of his skull.
“it was, uh. my heat hit hard while i was out and someone helped me, and then ended up uh. helping me.” He muttered, blush darkening.
Undyne instantly bristled. “Who?” She demanded, protectively.
Sans raised both hands, palms out. “no, no, it was all consensual!” He insisted, breathing a little easier when Undyne relaxed a little. Sometimes he forgot how protective Undyne could get over him, originally believing it was an extension of her desire to protect Papyrus. It took until he got jumped by the Bunny gang one time that he saw that fury be raised purely in his defense.
The Bunnies took quite a while to recover from that attack.
“W-with who, then?” Alphys asked, curiously peering at the tiny bundle.
“uh…” He hesitated, bracing for anything. “her name is emery.”
Undyne looked confused. “Who the fuck is Emery, I never-” Realization dawned, alongside incredulous disbelief. “No. Way.”
Alphys still looked confused. “Wh-what i-is it, honey?”
Undyne snorted a laugh, clapping a hand over her mouth to muffle the cackling.
Sans rolled his eyelights. “it's not tha’ funny….” He mumbled.
Undyne took a deep breath, the sound whistling through her hand. Held it. Let it out shakily, and then peeked open the fingers enough to whisper the word “human” in a high-pitched voice that sounded nothing like her usual self.
Alphys immediately froze, then began vibrating in place again. “Oh. My. Stars.”
“oh my stars, indeed,” Sans thought, sighing heavily as he braced himself for the influx of questions that he knew were incoming.
It was going to be a long night.