Toriel and Frisk quickly saw the skeleton brothers' house as their home. Of course, moving in didn't happen as smoothly as it could have, if only when it came to choosing where the human and her mother would sleep.
At first, Sans and Papyrus agreed to share the younger brother's room and leave the second room to their guests, for one because Sans rarely ever slept there anyway, and for two because it was easier for him to move out. The arrangement almost worked, despite the horrified scream Toriel made when she walked into the room and met the piles of dirty laundry and trash littering the floor. She immediately started cleaning, leaving Sans's room in a much better state than she found it in, with Papyrus's help. The taller skeleton almost cried tears of joy when she washed all the dirty socks and when the naked mattress was covered with clean sheets for the first time in forever. When Toriel asked Sans why his room was in such a poor state, he dodged the questions with a bad pun she forced herself not to laugh at.
The real problem only came later, when they had to take care of the self-sustaining trash tornado spinning in a corner that none of the three friends managed to stop, in spite of all the good will in the world. When Toriel asked with a dumbfounded face how that tornado even formed in the first place, Sans just shrugged as his brother pinched himself between the eye sockets. Those two skeletons were something, that was for sure.
Papyrus eventually decided to have Toriel and the tiny human move into the guest room. He'd just have to build a new toolshed. There was (a lot of) work to do and they had to step into the snow to walk to the living room, but it'd probably be a lot better than having to sleep with a cyclone rattling against the walls.
Please note that, although she accepted the arrangement, Toriel later came back regularly to check on her hosts' rooms. Seemed like she couldn't help but mother everyone.
The two brothers' garage, now officially Frisk and Toriel's home, received a good coat of paint, a brand new floor and a fill of furniture. Toriel had brought some of her own things from her house in the ruins, and Papyrus had taken out all the baby stuff he could find in the attic, until the new room was very warm and comfortable. After several days of interior designing, the goat and the child seemed to be ready to settle perfectly into their new life.
As Undyne had predicted, most monsters couldn't even think Frisk was human. For the few ones that could have suspected so, the adults had the idea of making a white onesie with a hood and fake ears, on top of which she could wear the traditional striped clothing children wore, therefor, if one didn't look too close, she looked like a baby furry monster. It was Sans who took care of the sewing, and the results were very good.
Of course, the Snowdin townsfolks were very intrigued by the newcomers. Toriel was worried she'd be recognized, but with New Home's overpopulation, seeing furry monsters moving in wasn't that surprising, and nobody seemed to question her size. As for her name, it was rarely ever mentioned in history books from the "librarby", which preferred to call her by her title, and very few people were old enough to remember her. It was almost shocking to realize how much time had passed since her exile. Depending on the type of monster, it could be several generations prior.
Generally, everyone was very welcoming of her and Frisk. Toriel was getting along especially well with Inny and Hoppy Keeper, the bunny sisters with whom she sometimes spent long afternoons talking about cooking and family. They would always gush about Frisk when Toriel brought her, and let her play in Inny's playpen, with her youngest child. That is, when she didn't find a way out and came back to pull on the skirt of her very surprised mother.
Frisk was an adorable and very affectionate child, but with a few weeks of good treatments and a little more flesh over her bones, she was a lot more active, revealing a curious, adventurous personality that her new family had a hard time keeping up with. The three of them were barely enough to watch over the little rascal that touched everything she could put her little hands on and was already trying to crawl up the stairs. Thankfully, she couldn't open doors yet. They were only half-joking when they said they were worried about the day she would learn how to walk. At least, there was always Alphys and her cameras.
Fortunately, they could always count on each other's help to take care of the child. Toriel generally had the priority, but when she had to go out or to do something, one of the brothers would take over. Papyrus was tireless and could play with Frisk for hours; Toriel trusted him enough to let him take the kid with him on his patrols. He'd sit her in his arms or scarf and walk through Snowdin Forest with her. Then, when she was too tired and needed some quiet time, it was Sans who took care of her. He'd read her a story, cradle her or let her play in peace with her cubes and plush toys, watching over her from a short distance. Eventually, when she'd fall asleep, he'd tuck her into bed.
Frisk found herself in the center of a comfortable day-to-day life, punctuated by visits at Undyne's of Alphys's. The fish lady actually had done her report to the king, and had told them he looked very moved, but mostly relieved at the news. He had decided not to take any hasty decisions, not to officially acknowledge the baby's presence, for now. Toriel didn't know what to think of her ex's decisions. She felt vulnerable when she though of him and always chose to change the subject quickly. She didn't want to imagine what that murderer was planning.
One day, at the breakfast table, Papyrus seemed even more excited than usual. He was frenetically scribbling on a paper sheet, and he had already darkened three of them, on both sides. Toriel noticed as she was feeding Frisk and smiled. "Are you preparing a new puzzle, Papyrus?"
"I'm doing something better than a puzzle!" the skeleton exclaimed with a bright smile. "I'm making a surprise for the tiny human, nyehehe!"
"What kind of surprise?"
"Well…" papyrus glanced at Frisk, who seemed more focused on her plastic spoon than on the conversation, and gestured at Toriel to get closer. He showed her his paper which was a list of diverse objects, such as a "sports car", "baby stilts", "a sidekick costume" or "the Fluffy Bunny books collection". "It seems, according to very certain sources, that Santa Claus will be in Snowdin today," he said with a hand over his mouth, like he was trying not to be heard by Frisk. "And since the tiny human hasn't met him yet, it is my duty to take her there. I, the great Papyrus, have prepared a list of toys to ask for her, for she cannot yet speak!"
"How nice of you," Toriel giggled.
"It is nothing! After all, the Great Papyrus should be the best guardian ever!"
Toriel smiled at him, thinking she hadn't seen time flow if Christmas was already growing near. The tradition of making presents that day had come from Chara, and had already spread through the Underground when they died. She didn't know if it had persisted elsewhere in the kingdom, but in Snowdin it had almost become a lifestyle. "Would you like me to come with you?"
Papyrus seemed to shudder, but it might have been her own imagination. "No need, I can take care of her myself!"
"As you wish." He really seemed adamant on bringing Frisk himself. Toriel thought to herself that she'd like to watch the scene anyway. Maybe she'd stay to make some sweets, then join them later. Sans might want to come as well.
He only left his room later, long after Toriel finished cleaning Frisk up, wrapping her in her baby monster costume, completed with gloves and little boots, and entrusting her to the good care of a Papyrus thrilled to spend his morning waiting for Santa Claus on Snowdin Town Central Square.
"Hello Sans! Have you slept well?"
"Uh huh, hi Tori," the skeleton just said, rubbing the corners of his eye sockets. He had only waken up three times that night and had fallen back asleep relatively fast, which meant that night was rather restful. Usually, there was no way he could choose when or how to fall asleep; he could spin around in his bed for hours at night, and then suddenly shut down while he was at work. Not that he did much about it. Taking care of the baby bones almost managed to regulate his internal clock. Who knew miracles could happen? Also, about the baby bones. "Where's the kiddo?" he asked, dropping himself on a chair.
"It seems Papyrus is taking her to see Santa." Toriel was kneading something – probably pie crust. "I thought we could join them later."
"It's Santa Claus day?" Sans wondered out loud. "Paps didn't tell me." It was unusual. Ever since he was little, he had been the one who took Papyrus to Santa, and he never forgot to warn him days prior. Even since he had been training to become a royal guard, Undyne would always give them a day off for the occasion. He never wanted to go alone.
"He certainly forgot. He seemed so excited to bring Frisk there, he even prepared present ideas for her," Toriel added, laughing as she remembered the list of eccentric gifts.
"Huh. Ok." Papyrus really was full of surprised. Maybe he just wanted to take up the torch by becoming the escort rather than the escorted. Sans felt a rush of pride for his little brother, mixed with a hint of nostalgia.
He chatted with Toriel a little more, shared a couple puns as he snacked on leftovers for breakfast, before leaving to slump down on the couch. Frisk would probably love to meet Santa, just like Papyrus did when he was little. He could already picture her sitting on the man's laps… Which belonged to the king in disguise, now that he thought about it.
He couldn't remember who took care of it before, but at this time, it was Asgore who usually disguised himself and came to Snowdin to have his beard pulled and listen to children asking for presents. Papyrus didn't know – he still believed Santa Claus existed. Should he warn Toriel?
After thinking it through, he chose to stay silent. As Alphys had told them, Frisk wasn't in danger for now. Papyrus would take care of her and worrying the former queen, or worse, taking the fun away from the kid, would be unneeded. The king wasn't stupid or cruel enough to hurt a child in front of the entire village.
Not to mention, as lazy as he was, Sans knew he wouldn't just sit back and watch if he felt even the slightest hint of a menace towards Frisk.