Trinity Stark: Your're welcome?

With the help of Toriel, Casey took over the task of trying to raise the two skeleton children. Papyrus enjoyed the puzzles in the Ruins, and Sans seemed to enjoy it there as well, due to the fact that it made Papyrus happy. Not knowing the day they were created, Casey asked the two if the day she had rescued them could be their 'birthday'. Papyrus eagerly agreed as did Sans, although the latter seeming less than pleased about the idea.

On the day of their 'birthday', Casey made them a meal of spaghetti as Toriel baked a butterscotch pie. From Toriel, both skeletons received robes that were similar to the goat monster's own, although both were slightly different. Papyrus's robe was more of a reddish purple, to match the red scarf that Casey had managed to knit-with Toriel's help, of course. And, having noticed how Sans had tended to stick his hands in the pockets of his hoodie or have the hood up, Toriel had added those to Sans's robe; although it was a bit too long for him. Casey's gift to Sans was a whoopie cushion. Although the smaller skeleton had been confused about her gift at first, Casey showed him how to use it. Sans tried it out on Papyrus, making Papyrus shake his hand as he held onto it. Seeing how it made his brother collapse in laughter, Sans always kept it close by.

One day, a few years after they started living in the Ruins, Papyrus was concerned when he couldn't remember anything before the boat ride from the Hotlands to Snowdin. Sans stated the same, and Casey realized she could no longer remember where she had first met the two skeletons. Despite the gaps in their memory, Sans was able to convince Papyrus to stop worrying about it… After all, some things were better off forgotten… After that day, Casey felt like the two skeletons could safely leave the Ruins for short periods of time as long as they were supervised, though the trips soon became longer and the amount of supervision slowly decreased.

Within the time that the group lived in the Ruins, two children fell into the chasm at separate times. The first was 10 years old, the second was 13. Despite protests from both Toriel and Casey, both of the children were determined to leave the Ruins. While Sans was a bit indifferent to the children leaving, Papyrus was saddened to see his new friends leave, and they never came back.

In addition, the solution that had allowed Gaster to speed up their growth made Sans and Papyrus age faster than monsters normally would. However, as they were reaching their adult years, their aging slowed down to the natural growth of a monster. While the skeletons had begun to age slower, the same could not be said for Casey… Although aging at the normal growth rate of a human, Casey fell ill shortly before turning forty. Several days later, she passed on… Leaving behind a glowing yellow Soul.

Although Toriel was saddened with Casey's death, Papyrus and Sans were devastated at the passing on of the one they had considered their mother; although Papyrus expressed his grief more openly than Sans. Toriel carefully retrieved the gently glowing Soul, storing it in an elegantly-carved wooden box and placing it on the table between the rooms of the skeletons and Toriel. The body of Casey was buried beneath the tree in front of the house.

Despite the fact that they had grown up in the Ruins, the two skeletons no longer wanted to stay without Casey. A few weeks later, the two were packing up to return to where they had lived long ago: Snowdin. As they were preparing to leave, Papyrus carefully packed the box that contained Casey's Soul with the rest of their things. Although Toriel did not approve, in case other monsters discovered it, she made no move to stop him. Within a couple days of being ready to leave, Papyrus had found them a place to stay, and the two brothers moved to Snowdin…

...Years later….

Frisk had decided to spend a few days with Sans and Papyrus before they headed into Waterfall. During their platonic "date" with Papyrus, the human had been able to explore almost everything in the room… Except for a carved, wooden box on top of Papyrus's bookshelf.

When they found themselves alone in Papyrus's room, Frisk borrowed the skeleton's computer chair and moved it over to the bookshelf. Climbing onto it, the human reached up to try and grab the box, but found they were still too short. Shifting to the edge of the chair, they managed to stand on their tiptoes and grab the edges of the box. Frisk managed to tug the box off the top of the bookshelf, and started to get off the chair. However, their foot slipped, and both they and the box began falling to the floor.

Ping.

A blue heart appeared on Frisk's chest as a blue aura surrounded the box, catching both before they hit the ground. "HUMAN! ARE YOU ALRIGHT?" Papyrus asked worriedly, hurrying closer as he held them in the air with his magic.

*Yeah, I'm fine.

"GOOD." Papyrus placed Frisk feet-first on the ground and the box was placed gently on the floor. Papyrus reached down, picking up the box.

*Papyrus?

"YES, HUMAN?" Papyrus asked, reaching up and placing the box back on top of the bookshelf.

*What's in the box?

Papyrus went silent for a moment, lightly touching his scarf. "... SOMETHING VERY IMPORTANT TO SANS AND I."

Frisk looked up at the box before looking back at the skeleton, crossing their arms over their chest. That didn't really answer their question…

"COME ON, HUMAN! THE SPAGHETTI IS ALMOST FINISHED!" Papyrus says, changing the topic as he put the computer chair back in its place. He then started heading toward the door.

Frisk glanced back up at the box, swearing they could see a glow of some sort emanating from the box… With a shrug, the human turned and followed Papyrus out…

... Surprise? It's the end of this story. Check out (zarla).(deviantart).com(/art/)(Stay-as-long-as-you-want-598128875) for a picture of the two with the robes on (IT'S TOO CUTE! X3). Thank you to everyone who read and enjoyed this story. I apologize for the chapter being so... Broad, but I was trying to compress 22 years into this final chapter. After all, other than a few major events, nothing will happen within the time they live there.

And while it may be the ending of the actual story, I still have a couple of one-shots to post. The one-shots are occurrences that happen during their time in the Ruins, to add onto this one.