undertale sans x reader

breaking the barrier

I woke up, not sure how much time had pasted since I, well, basically passed out. I checked my soul and it looked a little different, half human soul, and there was a new half growing beside mine, a monster half. I was amazed by the sight. I felt something solid behind me move as I was laying there staring at my soul. "Whatcha doin' staring at your soul, crescent?" I heard sans say in a groggy voice. "It grew a monster half, on the side where it was empty." I said slowly, sense he was still waking up. Sans suddenly shot out of the bed, and looked at my soul in amazement as well, his eye sockets wide open and was fully awake now. We sat there in silence watching my soul, the only light was coming from it as well. The silence was interruped by a knock on the door. I let my soul go back to my body and answered it to see Asriel and chara standing there. "Ready to go break the barrier crescent?!" They both asked at the same time, excited to go back on the surface. I smiled at their enthusiasm, but I pulled them inside and shut the door to ask them about their souls. "Yes I'm ready, but have you two checked your souls recently?" I asked them seriously. They both shook their heads no. I told them to bring their new souls out to see if what was happening to mine was also happening to theirs. They both pulled their souls out, Chara's was glowing brighter than a normal human's soul would, and asriel's soul was looking exactly like mine was starting to look. "That's strange, why are they looking different than a normal soul?" Sans asks this to himself more than he is us. I gulped, I knew why they were not normal, but if I spoke of it, he would know that this isn't the first timeline that I've had my idea, it's just the first time I actually tried it or even voiced it.  I decided to be honest and share exactly what I knew, knowing that sans was just gonna hate me later if he found out that I lied about not knowing anything. "Actually, this isn't the first time I've had this idea, I just didn't voice it in the past timelines because I didn't know if it was safe or not. This is the reason why I didn't voice it, our souls are reacting because they're all from one soul, mine, so they're trying to cope with your bodies and this causes some side effects to the original soul, which is mine that I have. If mine wasn't turning out half monster soul half human soul, then asriel, you would still be a flower, and if mine didn't glow so brightly, chara, you would still be in the void, Everytime the screen faded to black I met gaster, this is how I got his help for the research and why mine is glowing brighter than normal and growing a monster half to it. He did some tests on me while in the void before I reset each time, this was the only way I could contact him, was through resetting, or dieing and loading to a save file. During the tests, my soul would react and that's how we got a small monster soul growing inside my soul, kinda like how monsters have children, only, mine wasn't to have children, it was to make sure that my soul would be stable after splitting in half." I spoke while looking at the floor. Asriel and chara were shocked, sans was sitting there beside me, and I didn't need to look up at his face to know that he, was furious. "So after all that happened, why did you keep resetting?" He asked angrily. I took a deep breath. "Like I said, the monster soul was small, and needed to grow before I could split my soul in half. So after each run I did, I went back to the void, and gaster x-rayed my soul to check if the soul was ready. But, once it was, I..............I became scared that even though it seemed like it could work, I could've just wasted everyone's time and it could've failed, so I kept quiet about it for three timelines now. I knew gaster was furious with me for not carrying the plan out, like I promised, so in this timeline, I didn't just promise it, I swore that I would do it, and that's exactly what I did. I knew I made a promise to you sans, to not reset after the 59th reset, but I had to keep my first promise before I could keep yours." I let my hair fall into my eyes to prevent them from seeing me cry, I was never suppose to let anyone see me cry, that promise I made to my dad, but that didn't mean I couldn't cry in front of people, I just couldn't make it obvious that I was crying. I felt something tug on my sleeve, I wiped my face quickly and looked up and saw asriel was the one tugging on my sleeve. He gave me a sad smile. "At least you kept your first promise to me that no matter how many timelines it took, you were wanted to find a way to save me. And you stayed true to your word! It might've taken you a while, but it's better late than never!" He said with a cheery voice. Chara stood up next. "Yeah, and you said you'd find a way to bring me back without any hate corrupting my soul, and look! I'm here right now without corruption in my soul!" Chara said excitingly. I gave them a sad smile. They reminded me of my sister and I when we were younger. A part of my life that I have never regretted. Sans put his hand on my  shoulder and told me this. "I'm still mad you didn't just plain out tell me the truth of why you were resetting, but seeing how you were resetting for them, to keep your promise to them, I'm glad you kept it, and I think Tori and asgore are gonna be glad you did too. Just next time you make a promise, make sure it's not one you can't keep." He smiled at me. "It's not that I couldn't keep my promise to you, I just had promises to keep BEFORE yours, now that they're back and I stayed true to my promise to them, I have one more promise to keep before breaking the barrier, and that's bringing back gaster from the void." I smiled back at sans, knowing this promise, he would definitely help me with.