Undertale AU Oneshots

7. X-tale! Sans X Gem! Reader

Cross's eyes were different colors, as well, which you found strange, but cool. He had one white pupil, and one red. He also had a red, lightning-shaped scar under his red eye, and you'd never questioned it, though to you, the scar made him look cool. However, As for his weapons, Cross could summon a giant knife, and other knife-like weapons. He did have some magic, though, mostly teleportation and bone attacks as well. You had been so lost in thought that you hadn't realized Cross had said something, and you tilted your head slightly in confusion. "What was that?" You asked, and Cross sighed, meeting your gaze. "I said 'It's okay,I'm pretty sure you didn't mean to scare me.'" The skeleton repeated himself, and you mentally scolded yourself for getting so lost in thought. You nodded silently, and Cross turned away, making you notice the weapon he held. His knife. "Cross, where are you going?" You asked, thinking that maybe you shouldn't have asked that just yet. "I have to go take another universe." He said, gripping his weapon tighter as it gleamed with the little light in the room. "Can I come?" You asked, giving him a hopeful look, and Cross moved his gaze to you, his pupils darkening. "No. The universe I'm going to is much too dangerous for you, even if you are a Gem." Cross started to turn away again, but you reached out and gently grabbed him by the jacket sleeve, stopping him again.

"Cross, I really don't want to lose you. I-" Cross silenced you with a dark glare, carefully pulling himself out of your grip. "Fine! You can come with. But if you die, I'm going to be mad at you." You went over to stand next to him, and Cross's red pupil glowed as he started to teleport. "Trust me, Cross, you won't regret this." Cross made no reply to your words as the two of you teleported. You found yourself in Snowdin, and it wasn't as destroyed as the one you lived in. Most of the trees were still there. Cross pulled you close to him, and you stated to question it, but he quickly silenced you. "Hush, I don't want him finding us." The skeleton whispered, his words almost inaudible, and you went silent, not asking who it was. Cross dragged his knife through the snow as you followed him, leaving a long, red mark behind the both of you. It wasn't until a skeleton appeared that you froze, and Cross's eye glowed, as he tensed. "Fell." Cross snapped, and the skeleton moved his red pupils towards the other monster. "Cross. How many times do I need to tell you, this is my universe. You want to DIE?" Fell threatened, and Cross just stood there, his expression unfazed. You kind of regretted not listening to him now, because Underfell was one of the most dangerous universes, and you knew Fell Sans was not to be underestimated. If only you had let Cross finish...

Cross pulled his knife out of the ground, raising it. "I'm pretty sure you'll die first." Fell just glared, and suddenly, bone attacks appeared next to him, causing Cross to charge him, where he was almost immediately impaled. "Cross!" You shouted, your eyes wide as you watched him. The skeleton threw his knife before he fell into a kneel, managing to stab Fell with it. Fell, however, didn't even flinch. He just ripped it out, and threw more attacks at Cross. You could tell that your friend was going to be finished if you didn't do something, and you didn't hesitate to put yourself in front of him, taking the hit. Cross's eyes widened in shock as you winced, an attack through your chest, but not the gem."No, [G/n]!" You just smiled at him, though it was slightly pained. "I love you, Cross..." You managed, before you collapsed with a dull thud, only worrying Cross more. Fell glared at both of you, before he disappeared in a flash of red magic. Cross immediately knelt next to you, gently holding you close to him. The skeleton blinked back purple tears that were forming in the corners of his eyesockets, lowering his gaze. "Please don't leave me, I need you... I don't want to be left alone again.. Please..." He whispered, and though it took everything you had, you reached up and put a hand on his shoulder.

"Cross, it's okay. It was just my physical form, I'm going to be just fine." Even you were part human, more of you was Gem, so you would be able to reform. Cross froze, purple tears running down his face, as he paused. "What..?" He asked, and you smiled at him gently. "I'm going to be okay. Cross, when a Gem's form is badly damaged, they release their physical forms, and retreat to their gems to heal. Though, it may take a while..." You had never explained this to him, but you should have before now. That way he wouldn't have been so freaked out and worried. "Wait, so you're going to reform? But, that means you'll still be gone for who knows how long..." More tears slowly ran down the skeleton's face, and you gently wiped them. "No, Cross, please don't cry, I'm not leaving you! I'll be back, I promise. Just make sure you keep my gem with you. The most it takes is a couple weeks, it'll be okay. I'll see you again. Though it may look like I die when I explode into dust, but I don't. " Cross blinked away his tears, giving you a soft smile. "For however long it takes... I'll wait for you. I promise. I won't give up on you for a second." You were starting to lose your form, but you still managed "Thank you, Cross. I'll be waiting for you, too. Goodbye for now.." It was then that you exploded into dust, and Cross caught your gem before it hit the snow. He stood up, and pressed it close to his chest before he teleported, murmuring a very quiet "Goodbye, kiddo. I'll see you soon."

[Uh... Sorry about that one... It was a lot longer than I intended, too. I was planning to make her gem crack, but, I got a tear in my eye while writing that version, and decided it was too dark and sad. So, I erased it and wrote this. Plus, I would hate it if Cross was just left alone for the rest of his life. He would probably either die in a AU while trying to take a part of it, or he would slowly go insane, having lost the one he loved, and everything would just cave in on him, even if Chara did try to help him. So... I don't want that. I like this a lot better. Anyway, for the next oneshot I'm either going to do Echotale Sans or Birdtale Sans, I'm not sure yet. I also have some ideas for The Thought, but not enough to write a oneshot yet. I'm thinking more along the Echotale one, because I've sort of gone through the story, and I want to write it out. So, prepare yourselves. I'm sorry if I didn't stick to Cross's personality as well, this is what happens when you try to write something from a AU you just did reasearch on. But, I do like Cross, though he's not my favorite of the AU Sanses. I would have to say either Blueberry or Fell for that. And, the reason that the details are sometimes lacking, is because I think of what'll happen and I don't completely go through it like I do with fanfics. I really should start thinking these through a bit more..]- Quickstorm