All was peaceful in the Underground... That is, until a horrible disease began spreading rapidly amongst all monsters. It started in Hotland... Then spread to Waterfall... Finally, it has reached Snowdin. Sans never goes outside anymore. He doesn't even go to Grillby's, out of fear the disease will infect him and he won't be able to protect his brother in these dangerous times. All hell has broken loose... And it lurks just beyond the Skelebros' locked doors. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ WARNING: This fanfic contains horribly painful transformations, cursing, character suffering, gore and other content of that sort. Do not read if you are uncomfortable with any of said themes. Highest Rankings: #41 in disease #359 in papyrus #75 in undertaleau

This is a GasterBlaster!Underswap!Sans fic in the world of Underswap. Sans (or Blueberry) is a ten-year-old skeleton who isn't allowed to leave home. While his father (Gaster) does his job at a local party store, Papyrus is in charge of making sure his little brother stays safe and at home. But while Papyrus was out getting food, and unexpected visit came to their house, making the curious Sans, follow her and find out something that he had never saw in himself. I don't own Underswap or Undertale. Neither do I own the Gaster Blaster Sans AU. Hope you like it anyway! ^^