undertale sans x reader

doctor gaster

After the song event, we all headed towards the castle, sans keeping close to me and Amelia, just to make sure undyne didn't try anything. Once we reached the castle, we were greeted by King asgore, who was surprised to say the least to see Asriel and chara standing beside us. He let me and asriel by to the barrier, when we reached it, I saw a hidden white door, and being me, I walked over and opened it. There, behind the door, was the void. I looked back at asriel. "Keep this door open for me, I'm keeping another promise and going to try and bring gaster back, then we can break the barrier and be free. OK?" I told him. He nodded and grabbed the door. I entered the void and took a deep breath before calling out. "GASTER!!!!! ARE YOU HERE!!!!?" I called into the blanket of darkness. I listened for a soul melody and found one, it was sqratchy though. Found him, I had done enough resets to memorize gaster's, asgore's, asriel's, Chara's, toriel's, papyrus's, and sans' soul melodies. I followed the melody and found him, or rather, almost smushed (don't judge my terrible grammer alright!!) him, if I had not heard a groan. I looked down and saw my old friend, sitting there like a lump of a wotted black blanket. I smiled a little bit, before pulling out a syringe, and giving him a shot. Once the serum inside the syringe was put inside gaster, he optain a solid form and his soul was now put together as a whole monster soul. "H-how did you figure it out!?!" Gaster shouted surprised. I smile and just grabbed his hand, leading him out of the void. We got put and closed the white door that asriel was holding. Then, asriel and I approached the barrier, before using our soul's determination to break the barrier, freeing monster kind. When the barrier was broken, and monsters were free, I noticed that I was still wearing sans' jacket. I pulled the jacket off, before walking over to sans. "Here, sans, this is yours." I said before handing him his blue jacket. "Thanks, cress, and um, here." Sans held a black box toward me. I was surprised, it wasn't my birthday, and it wasn't a holiday, but nonetheless, I picked up the box and opened it. Only to be amazed by the BEAUTIFUL necklace inside. It was in the shape of a save point, and it was my (f/c),  (favorite color is what that means for those who don't know)
It was also a sapphire, they might not be as hard as diamonds, but they were still tough as hell. "I saw it and it reminded me a lot of you, the way you sacrifice everything that could make you happy and comfortable so everyone else can be happy and comfortable. The way you give up sleep for your sister when she has nightmares, and when you were helping the two kids over there, you could've died bringing them back, but nonetheless, you were willing to risk it for them. I like that about you, I like that you are so willing to help others, but I hate that you don't let others help you with the burden on your shoulders. And honestly, if it helps, I know how it feels to be like that, to think that you don't deserve help, that you deserve to do everything on your own, but trust me when I tell you, I'd like to be that special someone you can talk to, to seek comfort in. I.....I love you crescent. Will you be my girlfriend?" He asked, holding cheek in his hand. I was blushing reder than blood at this point.  I jumped forward screaming a loud, "YES!!!" just before kissing him. He was surprised, but kissed back.