My only one(undertale au x fem reader) oneshot

Chara: Star sanses x posses innocent reader

(The person who posses you is Chara. She's your older sister.)

I was sitting in this void with my sister. We ended up here one day when I was sleeping. Chara said I was very special because I can make portal and Summon weapon. I never use my weapons cause I don't believe in violence. Later after we've been in this void, I've been getting sleepy.

"Oh sis do you wanna go to Outertale. I've never seen stars before." I said with a huge smile. Chara turned around and patted my head. "Sure." She replied as I made a portal with my fake magical scissors. We jumped through the portal. I looked in amazement seeing all the beautiful stars.

No one's POV

Chara was different from some of the other au's. Her soul was attached to (y/n)'s which explains her magic ability. Chara couldn't resist the urge to go to Austin and kill. She uses her little sister's body. It was the only reason why they live in that void. They we're wanted by the star sanses and the others. Chara never told (y/n) the real reason In fear she would think she was being used.

After awhile, they went to snowdin wearing cloaks. (Y/n) was getting cute clothes and shoes while Chara threatened the casher person with a regular knife. Chara finally killed the guy and hide the knife. "I got clothes for us, hey where's that guy?" (Y/n) asked looking around. "Oh he went to the back. He said we can have the clothes for free." Chara answered. (Y/n) looked at with suspicion before just shrugging the thought away. They both left the store with bags. "Halt!" A voice yelled. They turned around to see the star sanses. Chara growled and (y/n) smiled smiled. "Hello, who are you guys?" She asked. (Y/n) never know the star sanses due to Chara possessing her all the time. "YOU SHOULD KNOW, WE'RE THE STAR SANSES!" Blue said. "Cool name, I sense Irony." (Y/n) giggled. Ink was the first to attack. (Y/n) hid behind Chara making a barrier around them. "Sis are they the bad guys?" She asked as Chara nodded before possessing (y/n). She calapsed on the ground as the barrier disappeared. The star sanses were confused. Where did Chara go? They thought. They soon heard chuckling coming from the possessed (y/n) who slowly got up summmon a (s/c) knife. "You fools picked the wrong day to mess with us." Chara growled glaring at the star sanses through (y/n)'s eyes. "I see, Chara possessed her sister, but why?" Dream said out loud. "I mean no one has actually been able to hurt my sis, so I'm sure you won't be able to kill us." Chara said before attacking them.

Time skip to after fight cause I'm lazy

Chara was about to attack with knifes once more till she was knocked out. Chara fazed out of (y/n) as they both fell on the ground. "Was she just using her sister for her own satisfaction?" Ink asked before he sighed. The star sanses tied them both up leaving the bag of clothes in the snow.

Timeskip... ^3^

(Y/n) woke up first, looking around to find herself in Ink's house, tied up, on the floor. "I'm so tired." She groaned about to wake up her sister till Blue walked in. "(Y/N)'S AWAKE GUYS!" He yelled. Soon after Ink and Dream came in. "Good, you're awake now you can answer some questions." Ink said with a serious face. He couldn't be serious due to (y/n) being adorable as she sat there. "Are you aware that your sister as been possessing your body to kill for her own selfish reason?-" "Ink!" Dream yelled. They didn't want him getting straight to the point with her. (Y/n) smiled she would never, she only uses that when we're endanger cause her soul is attached to mines, so I can use her abilities." She said calmly. "Have you checked your LV lately?" Ink asked. "... No, why would I do that?" (Y/n) asked. Ink gave a sad look summmoning her LV. It was over a hundred. (Y/n)'s eyes widen. "That's... That's not mine." She told them "No, it's your sisters when she possess you." Ink said. He hated doing this her, but it was the only way. There was a groan as Chara sat up looking at the star sanses before seeing the LV  in front of Ink. "What did you do?" She growled glaring at Ink. "I'm telling your sister the truth." Ink said. "Why have you been lying to your sister about this? Are you just a sadist?" Dream asked. (Y/n) didn't want to believe what she was hearing. Her sister wasn't using her to kill people. Chara loves loves her and she loves Chara. That's how it's always been. They're lying. (Y/n) didn't know that she was on the verge of tears as she started to tremble. Was she being used? Does Chara not care about her sister?...Was she just a mistake like her parents also said? "Haha, you guys are just liars, Even Chara's lying. The world is a cruel place... I am a mistake." (Y/n) mumbled the last part closing her eyes shut as she looked away from everybody. Blue walked over to comfort her. "That's not true you're a great person everyone loves you." Blue said softly trying not to yell. "... You guys will pay." Chara said darkly as black substance came from her eyes and mouth. As that happened, (y/n)'s right eye turned red as the same black substance came out of her mouth. Dream quickly put Chara to sleep. As summmoned a portal to his castle. Bringing Chara with him as he jumped through. "I hate myself." (Y/n) said through her cries.