---(Y/n)'s Pov---

"So how long is this gonna take you?" Sans asked while flipping his empty ketchup bottle upside-down since it was empty. Having to explain everything again made me mentally sigh, but maybe giving him a timeframe for my work would keep him from crawling on my back at all hours of the day.

"A few weeks to put everything together. While on the Surface, I gathered the necessary tools required for this. However, there were several things that I couldn't get that were instead here, in the Underground. So once I retrieve everything here, I will need to put it all together."

"Alright. Since you'll probably need a place to that, you can stay at mine." He said with a small chuckle. I knew that he was going to patronize me over that, so I decided to just go with it. Papyrus was relatively harmless in my eyes, as long as you flattered him. Not to mention... once he were to learn that I wasn't lying, he'd probably become supportive. "Hey, Pal. You do realize that fixing the Core wont solve all these problems down here?"

"Honestly, Pal. It isn't my job to fix the problems of the Underground. I'm just here to fix the Core." Yes, I openly mocked his use of the name 'Pal'. Actually, I blatantly mocked him a lot...

"Heh. You know, I liked when ya used my name" He claimed, causing me to give him an odd look. Why would he like me using his name? This skeleton was honestly too much for me.

"And perhaps I was hoping that you'd give my name the time of day."

He paused for a moment, completely stopping in his tracks before once again scratching at the crack in his skull. "(Y/n)."

"Yes, Sans?" The skeleton gave me a half lidded stare while once again continuing to walk. I wasn't entirely sure, but he maybe seemed to be... somewhat content.

"You have a nice name." And then there was silence. Well played, Sans.

As we both walked further into the cave of Waterfall, we could hear the sound of rushing water. Thankfully, my senses weren't drowned out when I grabbed Sans by his hoodie and pulled him out of the way of a shadow that was about to hit him. "The fuck-"

He had no room to argue over my actions once he saw a rabid looking creature in front of us. He was yellow with a stripped shirt and empty starving eyes. From my list of names, I could point this new face out as Monster Kid... only he looked much larger and definitely feral. No words were spoken by him, and Sans merely stood in place with astonishment by my willingness to pull him out of the way.

Engaging in combat with Monster Kid who gave me a starved growl, I simply gave him a cold glare. Since I didn't want to hurt him, I selected the 'Act' button. "Back off, we do not want to fight you."

And then, he attacked. Using his turn to try and slash at me with his clawed feet, I dodged out of the way. My evasion was elegant and very professional, even Sans could see that. Unlike with the dogs, I didn't want to show off my high LV in order to intimidate him. Sans' reaction was too unpredictable for that. MK's mouth was dripping a black substance, showing that his hunger was in full control... how can I approach this?

"Just kill 'em." The skeleton urged. I shook my head at his proposal and kept to my evasive movements. I wasn't a killer anymore- I refused to take another life. Since I was so focused on dodging, I never noticed the expression that the skeleton gave me... it was confused, but yet, nostalgic at the same time.

Eventually, Sans sighed at my lack of willingness. I could hear his magic come into play once he stepped into the battle to take his turn. Snapping my attention towards him as a blade flew past the side of my head, it landed directly into the chest of the MK. The small Monster looked down towards the weapon lodged in his body, making a gurgling noise as blood began to pool beneath him.

When I turned around fully, I could see Sans in a throwing position with a wide grin spread across his face... wider once Monster Kid turned to dust. It would be accurate for me to claim that he found pleasure in the death of Monster Kid, especially since his LV went up to 66. He had much more EXP than I did...

How was I, a former killer that chose to become a pacifist... going to work with him? A psychopath that wanted to kill everything that got in his way. "Heh. I didn't miss this time."

Yeah. At least he didn't hit me... but the way that he said it was different. Sans said it in a way that was unique- as if he was telling me to place my trust in him.

Instead of telling the skeleton that he didn't need to kill MK, I simply pretended as if it never happened. Death wasn't new to me, so why would this bother me? I refused to kill others, but that didn't mean that Sans couldn't do it in my place. It did make things quicker... but still. Even if I managed to talk the small Monster out of his frenzy, I doubt that it would of changed the outcome. Sans would of still killed them.

Casually, Sans strode up beside the pile of dust and picked up his weapon... as if nothing had happened. And moments later, we were continuing through the cavern at a steady pace. Both of us were fairly quiet, but yet, consumed by a comforting silence.

His single crimson eye would occassionaly glance in my direction to insure that I was still following him, and then would quickly look away upon making eye contact with me.

Soon enough, the path was starting to become much more damp. The skeleton was quick to grab a tattered ubrealla which he shoved into my hands before pushing me forward. He never grabbed one for himself, and instead used mine. "There is a secret piano past this statue, opposite to a different one that plays the statue's theme."

"Oh? What kind of piano?" he asked with interest. I knew that it was going to be very forgotten down here, probably even slightly off key.

Not responding to him, it didn't take long for us to come upon the unique room with a black piano. It was unfortunately tattered, but still appeared to be functional. "Is there some clue for the notes?"

Despite him asking this, I immediately went to play the piano. The song that was being done was known as Gaster's theme... very unique and played extremely well by me. The instrument reverberated through the cave, producing a beautiful yet eerie sound. For the period of the melody, Sans was heavily fixated on me.

When it was done, there was a shift in the wall... and soon, a passage way appeared.

I confidently strode inside of the small entrance, only to come upon a vast amount of tools and small mechanical pieces. "That song was familiar."

"Anyone could say that." I responded with a sigh. After a few minutes of searching, a came across a stabilizer chip. Literally a small piece of the project, but extremely essential. "Next is the true Lab... and perhaps I can find some additional blueprints while there."

"That won't be possible, bucko." The skeleton suddenly said, his red eye turning into a half lidded stare while he readjusted the weight of his axe. Looking towards him cautiously, he had a sinister smirk that told me to play my next words as cautiously as possible. If I didn't prove useful, then I was seen as dinner in his eyes... even though he was still very curious about me. "A unique energy reserve was supplied to the True Lab elevator, but the password to access it has high security. I couldn't even get down there when everything went to hell."

He took a step forward with a dark chuckle. As a result, I gave him my neutral face of disinterest. "And who knows? Maybe the amalgamates have completely lost it."

Before he could raise his axe, I started to walk off in the direction of the Lab, but not before giving Sans a cold glare. "I have the password."

He stopped once again to look at his reflection within the blade, easily identifying his murderous posture. "Oh..."

Scratching at his empty eye socket, he didn't return to my side... and I really did not care at this very moment. Walking through Waterfall alone, I was left with the sound of dripping water. I came across several blue flowers that were covered in specks of grey dust. Some Monsters must of relayed their dying wishes to the flowers before death.

Touching one of them, it gave me it's message... and maybe, just maybe... I felt the slightest pang of sorrow. "Please... someone save us."

It echoed through the room... taunting me.

Deciding to evade the words, I got up and continued on my path. Soon enough, I came across a different room that was not lit up by beautiful rocks on the ceiling. in fact, everything was very dark. Managing to take a closer look, I noticed something. The once beautiful rocks that served as stars were turned as black as coal...

Did the Core's magical regulation make the stones light up? How sad... I missed a beautiful spectacle.

Shaking my head, I continued on my path. Things became more warm, until eventually I could see the faint glow of lava in the distance. The next thing I saw was another sentry station... but no irritating skeleton to accompany it.

Taking a look back, I noticed that Sans was not following me... and that made me feel somewhat anxious. Was he planning something? Or did he maybe decide to leave me alone? Wouldn't that be a blessing.

Coming upon the bridge, my sense of perception told me that it was heavily unstable. I wasn't going to risk crossing because it was an obvious trap- one that would undoubtedly lead to my death. "Don't move, Human."

A hostile voice said. Turning my head slightly to see a Monster fully dressed in metal armor, I assumed this to be one of the Royal Guards... he had a dangerously sharp spear with him too. Honestly, I was getting tired from all of this walking and didn't stop to take a break. Nor would I dare to admit my exhaustion since it would be a sign of weakness.

Looking at the situation carefully, I returned my stare towards the pit of lava. There was no way to safely cross this bridge, and by now I would be forced to fight. Revealing my LV to deal with the guard wasn't an option that I wanted to consider, especially since he might not back down to me.

A sharp sound of his metal scraping caught my attention, followed by a deep husky voice... "Hey, pal. Long time to see."

"S-Sans?!" The guard immediately dropped his weapon in panic since the skeleton's weapon was firmly pressed up against his throat. Maybe his armor was protecting him, but Sans was still very dangerous... and we both knew it.

"Heh. What's wrong? Is something bothering ya, bud?" Without having to turn around, I could hear the comical sarcasm that was laced in his words. "Ah... maybe it's the fact that you tried to help Queen Undick take my eye? Yeah. No hard feelings, right?"

"Righ-"

"Wrong." Sans stated with a small chuckle.

"You see that human there?" By now, he slung an arm around the Royal Guard as if they were old time friends. He pointed in my direction, causing the enemy to nod carefully. "Well..."

"I made a promise to her. I told her that I wouldn't guide her to her death..." And with that said, he shoved the Guard to the ground and grabbed his hatchet. "And I ALWAYS keep a promise!"

"One headdog... "