Gaster and Grillby's house was very tidy. Sans has been close since the thing with Kane. You didn't blame him. He only left to get clothes and etc when Gaster or Grillby was home. They were both capable monsters he trusted to protect you, after all. At the moment, Sans was simply enjoying listening to the baby in you, his tail always wagged every time he kicked. "How sharp were your claws as a kid?" He shrugged. "not all that sharp, it was my tail. don't think he's whipping that around in there though." His tail wagged again. "Has it ever occurred to you that he's kicking you in the face?"
"meh."
"Maybe he's saying your to close and he wants to be left alone." You mused. His eyes narrowed. "this is your father speaking, [C/N]. kick me if if you don't want to be left alone." You stiffled a laugh. "You're such a dork." His tailed wagged yet again. "ha! he's ok with me!"
"This is your mom speaking, [C/N]. Kick him for being a dork."
"who's the dork now?"
"I read that talking to your baby while he's in the womb establishes a sense of familiarity when he's born."
"no kidding? heya kiddo, your dad again, i love ya to bits already~"
"It's your mom again, we both love you!" You cooed. Gaster stepped in. "You're both dorks."
"rude." You laughed.
*********************

You came down for breakfast the next day, Gaster and Sans were sipping coffee. "No chains? Grillby not home?"
"He's working overtime today." Gaster replied. You hesitated a moment. "What happens if he's born like Sans? Will he have to go through.. testing..?"
"i've actually been thinking about that. chances are he will be born like me, but will also have control as i do. it's in our magicline now. once that happens.. i guess i'm gonna have to fess up to the others."
"The sooner you do, the easier." Gaster commented. "I will be there too, to tell my part of the story."
"As will I, as your support." You promised. "gracious, your the absolute best." Sans put down his mug, padding over to nuzzle into you. "i love you so much." You kissed his skull. "I love you too, Sans. "mine~"
"Sans.. you haven't even marked her as yours yet." Gaster broke into your moment. "Mark?" You asked. "eh heh heh.. it's a small spell of sorts a monster buts on his or her mate to tell other monster you are theirs.. it's kinda like having a wedding ring so humans can tell your married.."
"Why haven't you marked me yet?" You asked. "i was gonna.. but i went into rut, got distracted with [C/N].." He chuckled. "we can get that done another time. right now, we should focus on my, uh, confession."
******************

Once more, everyone gathered at Gaster's place this time. Sans had the chains on, and was pacing the guest bedroom nervously. At his fifth time around, you caught him. "Sans. It's ok. I'm here." You hugged him close. "what if they hate me, what if they fear me, what if they hate [C/N]? you kid should live with that and it will be my fault!"
"Sans!" You gripped his hands firmly. "Do I hate you?"
"no..."
"Do I fear you?"
"no, but-"
"Do I hate that we are having this kid, our kid?"
"no."
"I love you. We all love you. They are your friends, your family. They can never hate you. I can never hate you. Gaster's downstairs right now, explaining his side of the story." You grabbed the key to his cuffs. "You can show yours. I'll be with you every step of the way." He whimpered, Hugging you close. "i love you so much.. your so kind to me.. thank you for loving me, gracious.."
"Always and forever, Wild." He took the key and you both left the room, hand in hand.
*******************

Gaster must have just finished. "SO.. MY BROTHER IS.."
"Feral. Yes." Gaster confirmed. "I-I.. that's quite the accomplishment.." Alphys stuttered. "Is that why we found Sans in the True Lab?"
"Yes." Gaster confirmed again. "Where is he now?" Toriel asked. "i'm here.." Sans spoke up, drawing everyone's attention to him. You squeezed his hand. "You've got this, Wild." He smiled a little. "i, uh.. i'm gonna back up my dad's claim." He pulled off his jacket, revealing his cuffs. "these are specially made cuffs, i created to suppress my magic so i can look normal. uh.. i'm probably gonna make a pair for [C/N] too so monsters don't.." He trailed off and you squeezed his hand again. It seemed to reboost his confidence. "a-anyway, i'm gonna take 'em off now so you can see for yourself." He inserted the key and the first cuff dropped. His eyelights flickered gold. He inserted the key into the next cuff and his eyelights disappeared all together. He did the same to the final cuff. His eyelights came back as slits. You hugged him. "You did it! I'm so proud!" He chuckled. "i did do it.." He hugged back, tail wagging. "i did it! i didn't back out!"
"No you didn't!" Gaster cleared his throat. "The audience."
"er, right.." We quickly turned back to the surprised, gathered monsters. "uh.. questions?" Papyrus shook his head. "WOWIE.." He immediately crossed the room and picked Sans up in a hug. "So how strong are you really, Sans?"
"I had no clue this was remotely possible."
"And the baby is going to be like this?" Sans was busy being crushed so you answered for him. "Stronger then you ever want to find out, this is possible, and most likely."
********************

You were getting ready for bed for the night. "so.. about the conversation earlier.. do ya wanna be marked?" You looked to your mate. "What's it like?"
"the experience is different for everyone. some say it hurts, some say it's pleasurable, some say they felt nothing. the mark is put directly on the soul, so.." He shrugged. "Could I mark you?" He shook his head chuckling. "sorry love, monster thing only."
"Aw." You pretend pouted. "heh. so, what'll it be?"

Be marked?

Wait?