The Amalgamates are a group of monsters who were brought back from the dead when Dr. Alphys injected them with Determination. Unfortunately, while all was initially well, monsters do not have enough physical matter in their bodies to handle copious amounts of Determination, and thus the subjects began to melt and merge with each other. Ashamed of her failure and guilt-ridden that she could not successfully return these monsters to their families, Alphys confined them to the True Lab in order to keep their existence a secret from the rest of the Underground.