FIXED Gaster is the entire cause of the FIXED AU. after 6 genocide runs and sans dying 6 times, he figures out that there is no way that sans can stop the human from continuing. So he steals Sans, experiments on him, and then figures out what Alphys couldn't. he realized that the monster body could not withstand any amount of determination, it was not made to, but machines could harness it. so, he made a machine that could harness magic and determination. But, instead of mixing the magic and determination, he kept them separate. Sans' left eye was full of magic, so he needed to mechanize sans' right eye to hold determination, and while he was at that, he mechanized about half of Sans' body to hold determination within it. the mechanized parts of Sans now hold determination, and the regular parts hold magic. The ULTIMATE MONSTER. Sans was now... Fixed. so, Gaster programmed Sans to gather the rest of the monsters and send their bodies to him. He also had to make a way of preserving a monsters body, so after killing a monster, Sans infused them with magic so their physical structure could stay together. Gaster then proceeded to FIX all the other monsters except weak ones. It was a success, the human now died multiple times, not ever finishing the route. And never being able to escape. But, something unexpected happened. Asgore, the only one with the soul able to completely destroy the barrier along with a human soul, Died. Now, unable to open the barrier to escape, he was drove mad. Now his only objective is to kill the human as many times as possible.