Yandere!Under verse x Reader

Timeline 1

A/n: just for a little clarification, the previous timeline XGaster talked about last chapter was him giving up hope, and then Ink showing him the doodlesphere. The reason Y/n got confused was because there wasn't any memories coming from XTale before, so "hearing" memories from that AU, was confusing for them.

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Y/n had gotten bored and curious, so they decided to visit that strange au in curiosity, but they did make a little something to make some things easier. They made a small, perma ice snowflake. The snowflake is a way to contact them in case you need Y/n. All you need to do is press on it and think why you need Y/n's help, and the snowflake will glow, signalling that they got your message and is on the way! Memory actually taught them that trick, but his snowflakes melt after 10 uses, so you gotta use them wisely! Where were we? Ah yes, Y/n visiting XTale.

Y/n made an ice portal and went through it, using some of their memory magic to make it seem like they are invisible to others. Y/n sees that there is now a city on XTale, and gets curious, wondering if XGaster used his power to create this. Diving down, Y/n glides through the city, exploring. Y/n sees a lot more people and monsters, and feels that their memories are all good memories, nothing bad happening...but that makes Y/n suspicious because there is always a bad memory in someone's memories, whether they admit it or not. Y/n then suddenly feels a negative memory forming, and flies to where the source is coming from. Y/n spots XGaster, XFrisk, and XChara standing infront of what they can only assume is XAsriel. Y/n lands behind all of them, noticing that XFrisk is looking away, crying, and XChara looks shocked with tears in his eyes....and XGaster looks like he isn't feeling anything.

XAsriel: Chara, Frisk. My dear brothers. Please don't be sad. We'll see each other again. We can play and laugh together just like we did in our childhood. You two will be a hundred times happier than this. It's a promise, okay?

XGaster summons the OVERWRITE button and Y/n gets suspicious, their tail lashing slightly. XChara looks shaken, looking at XGaster, before looking at XAsriel.

XAsriel: Stay determined, for our freedom.

XGaster presses the button, and everything in the au disappears, except for XChara and XFrisk, who have turned back into children, XGaster, and Y/n. Y/n stumbles abit, the sudden lack of memories jarring. XGaster turns, having heard them stumble, but Y/n teleports into the air, knowing that XGaster won't see them because of their memory magic, but they still don't want to risk it. Y/n frowns, seeing XChara and XFrisk cry, so Y/n attempts to cheer them up, sending good memories of their time with their family and friends to them. It seems to cheer them up, and Y/n notices the golden heart-shaped locket on the ground, figuring that the item will be important. They can feel the memories coming from it, so Y/n will have to grab it later for safe keeping in case XGaster tries something.

~~mini timeskip~~

Y/n has stayed in XTale for the rest of the day, watching over the three inhabitants of the au. XChara had grabbed the heart locket, so Y/n doesn't see a need to grab it. Y/n keeps watching them, well aware of the two children sleeping and XGaster staring at the OVERWRITE button, before looking up.

XGaster: I know you're there, reveal yourself.

Y/n curses under their breath, but reveals themselves, the memory magic falling off of them in a flurry of snowflakes that wakes up the two humans.

Y/n: XGaster.

XGaster turns and sees Y/n there, their arms crossed. XGaster raises an eyebrow.

XGaster: why are you here? You've been here for a few hours, haven't you?

Y/n, nodding: I have. I came because I felt memories suddenly appear in this au, and came to check it out. I found that there was monsters and humans here, living in peace, so I didn't interfere. I went back to my home, and then came here once I felt a sudden lack of memories, and it was pretty jarring, if I do say so myself...*narrows eyes* so tell me, XGaster, why have monsters, humans, the city, and the memories of this au suddenly disappeared.?

XGaster looks at them, thinking. The two humans sit up, hoping that Y/n will be able to do something about XGaster.

XGaster: this world was not perfect. I can make it better, perfect.

Y/n, frowning: XGaster, there is no thing as a perfect world, it's impossible. If you take away any negativity and problems, then the people won't grow and evolve. If you take away and positivity and happiness, then all of the people will just be miserable and not do anything! If you take away their memories, then they just become mindless puppets! There is no thing as a perfect world! There has to be a balance!

XFrisk and XChara look at Y/n with hope in their eyes while XGaster narrows his eyes.

XGaster: With the overwrite button, I can take people's suffering away. They won't have any problems and everyone will be happy.

Y/n shakes their head, disagreeing.

Y/n: Then they won't grow and evolve. They won't think of new things to make their lives better. Humans have DETERMINATION, so they won't stop until they achieve what it is that they are looking for! Yes, monsters have DETERMINATION too, but it's more unstable for monsters! It'll destroy you!

XGaster: Silence! I am doing what's right for the children!

Y/n: Then why destroy everything? From what I could see from their memories, they were happy in the previous timeline, but became sad when you took that away from them! No one in that timeline, except for you, had bad memories! Just because you have doubts, doesn't mean you act on them!

XGaster, eyes shadowed: I think you should leave, Y/n.

Y/n, narrowing eyes: I think you should not interfere with others lives. I do have to warn you though, XGaster, if you keep taking away people's memories like that, then I will interfere.

XGaster turns away, being abit too stubborn to admit when he is wrong. Y/n sighs and turns to the two humans, who are looking at them with awe and hope in their eyes. G;ancing at XGaster, Y/n sighs and shakes their head, making two of the snowflakes and handing it to XChara and XFrisk, who take it gently, eyes wide with awe. Y/n smiles.

Y/n: anytime you need me, you just press the snowflake and ask for me, alright? The snowflake won't melt, and I did make it so if it gets lost, or someone takes it from you, then it'll just return to you, alright?

XChara, eyes wide: T-thanks...

Y/n, smiling: anytime!...but I do have to leave now, before XGaster gets more angry at me...well, I'll see you around. Call if you need me!

Y/n makes an ice portal and hops through it, leaving the au. XChara and XFrisk look at the snowflakes in their hands, feeling DETERMINED to stop XGaster from ruining their happy ending...and hey, who knows...maybe they will get their happy ending, even if it takes awhile..

Word Count: 1262