Undyne x Female reader

Chapter Eighteen: Planning

~(Y/N)'s POV~
I watch as Undyne laughs with Alphys and Papyrus while they tell funny jokes and stories. I crack a smile for the first time in a few hours, but it quickly fades away. I look down while I remember me and Undyne pulling a prank on Asgore.
~Flashback~
Me and Undyne chuckle while we sneak into the castle with a piece of cherry pie. We went behind Asgore while he talks to some counslers about what could happen in the future and how we should be prepared. Undyne smirks and hands me the pie. I slowly walk up to him while Undyne casually walks up to Asgore. "Oh! Hello Undyne! Anything to report?" Asgore said while I climb up his back, surprised that he can't feel my weight on his back. "No sir! I just needed to check how the guards are doing. Are they doing well?" Undyne asks while I swing my legs over Asgore's shoulders. "Well, their doing quite fine! But Papyrus gave everyone that has the highest skill food poisoning so we had low numbers for about a week. Other than that, their fantastic!" Asgore said and when he finished his sentence, I smashed the pie in his face. Me and Undyne laugh while I jump into her arms and we run away, Undyne carrying me bridal style. "(Y/N)! UNDYNE!!! YOUR SO DEAD!!!" Asgore yelled but that just made us laugh more.
~Flashback~
I smile at the memory. "HUMAN! IS SOMETHING WRONG?" Papyrus asks while I looked around Alphys' lab. "O-oh! I'm fine! Just, a little distracted, that's all!" I said nervously. They gave each other looks before shrugging it off and went back to talking. I sigh in relief before going back to my thoughts.
~Sans's POV~
I sat there while thinking. Maybe if I go to Alphys lab then I can put the right time and place where (Y/N) is. I'll have ten minutes to find her and bring her back. I just hope it won't take longer than ten minutes I thought while playing with my fingers. Yeah, I'll go at midnight when everyone is asleep. I just hope I don't run into Chara.
~Time Skip~
It was midnight. I hear soft and loud snores, meaning it's time. I open my eyes and look around just in case before getting up. I carefully step over monsters and towards the door. I carefully pick up Alphys and move her away from the metal door since she was in the way. I slowly open the door and slowly close it so I won't make any noise. I walk down the mountain, hearing the snow crunch under my feet. I soon hear footsteps. I quickly hide behind a tree when the footsteps became louder. I look over the tree to see

Chara.