Sorry for such a delay on this chapter! I tried something new with this, and there was a lot of ideas I wanted to get in for this

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You would be back, you had to be. You sat in the black void with the two buttons floating in midair, continue or reset. Frisk nodded, signaling they wanted to reset too. The two of you hovered your hands over the button, as a full soul was required, you would press it at the same time. With a deep breath, you pressed the reset button. The world faded to white as you felt the void disintegrating under your feet and you felt a familiar falling sensation. 

As you fell, the world around seemed to be infinite, with swirling colors taking the form of vague memories of the past. The colors got brighter, and eventually turned to white before you passed out. 

A soft bed of flowers broke your fall, like they had before. Frisk was no where to be found, something seemed off about their absence. You sighed and slowly got up, walking to the next room where you would have been greeted by Flowey. Where he should have been was nothing but golden light. So even in the reset, there were consequences.  Toriel greeted you to the ruins, but somehow Frisk was not with her. 

Toriel would guide you back to her home, where you found Frisk sitting near the fireplace and reading. They waved to you upon seeing you walk into the room.  But you both knew you would have to leave Toriel to progress to the rest of the Underground, so you and Frisk asked her when you could go home, until she got up and went downstairs, saying she had something to attend to. You and Frisk followed her, refusing to listen as she told you to go upstairs. 

"Fine then, prove to me you are strong enough to survive!" Toriel yelled, summoning fire around you and Frisk. After a bit of fighting, if you could even call it that, more like sparing her every turn and her eventually not wanting to hurt you any more and making all her attacks dodge your half soul. Toriel spared you, and let the two of you go. But not without a condition, don't come back. You and Frisk agreed to this and gave her a tight hug before leaving the ruins. You walked down a long purple hallway and to a door that led to a cold and snowy environment. 

When you got to a bridge, you paused upon hearing light footsteps behind you. Frisk gave you an  I-know-who-it-is kind of look before turning around. You turned around too and saw Sans there. You wasted no time and hugged him. 

"I missed you." You said, burying your head in the light yellow fluff of his jacket. Sans hugged you back, a light blue blush appearing on his cheekbones. 

Time skip cuz I need to get this chapter out before 90 day fiancé is on~

Sans decided to walk around Waterfall with you and Frisk. The latter walking ahead and taking in the surroundings. You were older than Frisk, and the way the three of you interacted...it made you feel like you were...a family. The age gap was strange, since you and Sans were 18 and Frisk was 11, but it still felt nice to be like a family. You got to a room with a curled up statue, rain falling on it. Frisk walked to the next room and returned with an umbrella in their hands, what were they doing? They placed the umbrella over a statue with a small smile. Frisk sat down next to the statue as a music box began to play a calming tune. A few minutes later, Frisk was asleep. You giggled and picked them up, looking at Sans and smiling. It made you wish you could raise Frisk as your kid. Maybe once you broke the monsters free from the Underground. 

Walking around Waterfall with Sans and a sleeping Frisk was so comforting. They seemed to be really close to Papyrus. You sat down next to a lake of glowing cyan water, sighing. Sans sat down next to you, asking what was wrong. 

"Well, what if we...raised Frisk as our child...? I know it's super abrupt but it would be nice." 

"I'll be right back, it we're going to raise a child, there's something I need to do first." Sans said, disappearing with a blue flash. He returned a few seconds later, looking extremely nervous about something. He held his hand out to you, you took it and looked into his eye sockets. Sans took a deep breath before saying:

"Y/n, I love you so much, and if we're going to be a family, I need to at least ask..." he trailed off before getting on one knee, holding your hand and taking a box out of his pocket.

"Will you marry me?" The ring was [description of your ring]. Without any hesitation, you said yes and kissed that adorable skeleton. What would Frisk think? You didn't know. They woke up about an hour later, asking what happened while they were asleep. You held out your hand with a ring on it, smiling shyly. 

"You're marrying Sans!? Oh my god when's the wedding!?" They exclaimed. You and Sans shrugged. 

"Looks like it's almost time for you to fight Undyne, she'd have my skull if she found out we were together, let alone engaged, so I'm gonna go home and tell Papyrus. Good luck sweetheart." Sans said before teleporting away. The overhanging feeling of dread overtook you as you neared a mountain, a figure looking out to the rest of the Underground. When you got closer, the figure turned around and looked at you and Frisk, it was Undyne. She immediately jumped down, summoned a spear, and held it to your soul, since Frisk was hiding behind you. 

"For ages, we've dreamed of a happy ending. I'm not letting you ruin this for us!" Undyne screamed as the world went monochrome and a fight commenced. Your and Frisk's souls turned bright green, for kindness. You couldn't run away, only block attacks with your bright green shield. Whenever your soul went back to being red, Frisk grabbed your hand and you practically dragged them along with you as you ran. Frisk was a slow runner, so you pulled them with you through a path in the mountain and to a much hotter area. Sand crunched under your shoes as you ran along with Frisk. You passed a small sentry station, where Sans was sleeping. You smiled slightly and kept running over a bridge. 

Undyne collapsed on the bridge, and being a fish and all, she couldn't handle the intense heat of Hotland. Frisk walked over to a water cooler that just happened to be there, grabbed two cups of water, and walked back over to where Undyne was passed out and where you were standing. They handed some water to you and poured the other onto the passed out fish monster. Undyne slowly got up, scoffed at you and Frisk, and walked away without a word. Frisk took off their sweater due to the heat, revealing a plain, dark gray shirt. They tied their sweater around their waist and waited for you to finish drinking your water while they got their own. [same for you with the sweater if you wear one in this story] You walked up to a lab, the doors automatically opening to reveal a completely dark interior. 

You nervously walked forward, Frisk following closely behind. You stopped when the lights abruptly flickered on and a door to the side opened, revealing a short lizard monster. 

Sorry another time skip~

"Huh? How are we supposed to do this?!" You exclaimed to the general area of the puzzle. You had to jump on strong jets of air coming from the ground to get to the other side of the room. 

"Well, wish me luck!" Frisk said, jumping on one of the vents and flying up into the air, giggling. They landed gracefully on the next platform before jumping on another vent. It looked fun but in all seriousness you were terrified. Frisk beckoned to for you to join them on the other side of the room, so you sighed and jumped on the first vent...

A few moments later, you were on the other side of the room. 

"That was the scariest thing I've ever done." You said. Frisk giggled again and started walking around the area, you following them. 

~

After a short "date" with Sans at MTT resort, (you couldn't really call it a date when Frisk was there) you and Frisk were off to the Core...

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*slides chapter across table* AHHHHH so I feel like I rushed snas proposing so I might rewrite this chapter when the book is finished, anyways I'm getting right to the ending for this run, so see y'all in the next chapter!