I have an Idea for an Undertale AU. And apparently, it's a good idea? So here, have a book. --- Long ago, two races ruled the earth. But when a plague of corruption swept through one species, causing a half of their population to attack the humans, the humans thought it safer to banish all the monsters underground. Now, the Underground is a Battleground. The battleground of the Pure and Corrupt armies. This Is UnderCorrupt. -- COMPLETED!