(This is also Underswap, one of the ones I like. Also Underswap Amina is human and if I were to put Frisk in she'd be the wolf child.)
Sans groaned lightly as a little sliver of light came through his bedroom it was that and the distant barking of a dog in the neighborhood, Papyrus was up again at 4 in the morning, it wasn't the first time it's been happening for a long while. It wasn't everyday just twice in one week or once in a week, Papyrus would get up at 3 or 4 in the morning set up something in the kitchen, pack it up and leave. He'd come back later in the day at 5 or 6 in the morning and go back to bed. Sans had studied his older brother's habit and became rather concerned? No curious, Papyrus would be able to handle himself if in danger and this wasn't the case. What on Underground earth was making his lazybones brother do this? Today he would have to find out. Once the light was out and he heard the front door close Sans made his way outside to follow his older brother but not before tying on his beloved blue scarf, outside was still dark even if it was 4am there was no morning sun to slowly greet them, he'd have to find a human soon so everyone can see some sun, he heard it was the best thing to wake up to...if you were a morning person at least. Papyrus shuffled his hoodie a bit and stopped to look behind him after hearing a crack, but shrugged it off starting his stroll again as he soon made it to a nice small house, with white picket fence and odd little flowers they were pink, purple, white, and blue all on a different bush of flowers there was a small white dog outside as well which was asleep inside his dog house. The tall skeleton monster opened the gate from the lock behind it, soon climbing up to the porch, he dusted off his hoodie and rung the doorbell and after a moment a very flustered woman opened the door she laughed nervously "I didn't mean for you to come over Pap." She mumbled making him chuckle softly "It's no problem really, I just have to be careful as to not wake my brother up." At the mention of brother Sans peeked out from the flower bush and had to stop himself from shouting out "Human!" Because the woman at the door was just that, she looked young and vibrant. Head full of long dark brown hair, and wearing a nightgown of sorts, but what really caught his eyes was the way her stomach stood out just slightly gorged like she's eaten a lot more food than needed "By the way when are you going to introduce me to your little brother? I must meet the great Sans~" She chuckled as Papyrus shook his head the shorter skeleton hidden in the bush grinned wider with little stars for eyes 'This lady knows a great man!' "You know I can't, his eyes are set on capturing a human. I can't let nothing bad happen to you, I mean what if something happens to the-." The woman rolled her eyes and smiled "I'm sure once you explain things, he won't try to turn me in." Papyrus was about to walk inside but the woman stopped him "You can explain it to him, once he gets out of my Hydrangeas." Papyrus looked over to her favorite flowers as the small skeleton stood out of them and gave a slight laugh as his older brother sighed.

A bit later they were having breakfast, it was early in the day so why the heck not? "I didn't mean for you to come over so late Pap, I got a bit scared because there was a sharp pain...but I realized it was just some stuck gas." Sans looked up from his blueberry pancakes at those few words, Papyrus had placed a hand on her large belly making her huff and wiggle away "As I said, it's no problem. You need help more now and that silly bird of yours isn't most of it." The Lovebird on her shoulder cooed angrily at him as Sans raised an eyebrow he stood up making the chair squeak catching both both their attention "The great Sans wants to know why his brother kept the human woman a secret!" The woman in question looked over to Papyrus who looked away from them both clearing his throat to which earned him a flick to the forehead from the woman "Amina! Fine fine, Sans this woman is Amina. Amina this is Sans my younger brother." She smiled softly towards the short skeleton "For about a month or so I've been helping her. Toriel as well." He said as Sans waved his gloved hands about "So? What's the reason for you not telling me about her!? I can keep secrets to you know, I am the awesome Sans!" It was silent for a moment until Amina laughed "Why have you not brought him over here? He's absolutely adorable." The woman said hiding her laughs with her hand this though made the little skeleton blush lightly "Well Sans, I wanted to keep her in secret because Toriel told me too. There's a lot of dangers here that could hurt me and my little one here." She stated rubbing her belly gently to which made the little skeleton gasp and but the next question he had asked made his brother pass out and the woman laugh heartfully: "You have my brother's baby in you?!"

A bit after breakfast Sans was helping Amina clean her house Papyrus went out to get something she wanted. Sans fritted slightly for the woman what if she bumped into something or fell on her belly what kind of knight would he be if he wasn't saving the princess?! The short skeleton looked up to her as she hummed a song to clean too and blushed lightly "Say human woman? How did you met my brother?" The woman stopped dusting for a moment and looked over to the flamboyant skeleton "Oh it's a long and funny little story, but my little one here and Fido outside is what brought us together. Hey! Now you're part of this little family! Never to be bonely again." She went off on a different thing but he looked to her big belly then to her smiling face "I guess there is things to look forward to, even if things are bad huh human woman?" Amina nodded happily "I appreciate your brother for helping me along the way, and I wanted to meet you but I understand his protectiveness." Sans nodded placing his hand on her baby belly "Well don't worry human woman! You now have the awesome Sans on your side!" He exclaimed making her laugh "I sense that me and you are gonna be great friends. Now how about you set down with some cookies and I'll tell you how my little baby and Fido helped me with your brother."