Gaster is the current royal scientist, set with a mission to break the barrier and free monster-kind from their underground prison. His loyalty and persistence to the task is clear, since he'll make whatever sacrifice necessary to complete it. However, even a perfectionist can be blind to some of their own flaws. Gaster has a habit of pushing things or himself too far. An accident occurs in the lab. Whilst trying to save him; one of his lab assistants, Y/N, gets injured. Burdening himself with even more pressure and guilt to fix it, Gaster thinks that doing all of her work for her will cover up the incident. Still, the sad reality is that the damage can't be undone. Well, Gaster ends up spending more and more time with her. As a result, both of them gain an entirely new perspective of the other, they aren't just another monster in a lab coat anymore. Hey! It's Oreo aka Writer~San! Undertale, it's characters, and it's fanart do not belong to me. However, the story does!!! I hope you enjoy it! (^w^)~

This is a book full of one-shots. There will only be Sans(with Aus) x reader. No Sans x Sans.