Hyacinth
"You know, we've met before, actually." Gaster said, careful to keep his tone casual. Grillby looked up from the glass, and studied Gaster's face. "I don't... What did you say your name was?" Grillby said slowly, unsurely. "Gaster. I'm doctor W. D. Gaster." Royal scientist, father of Sans and Papyrus, and your goddamn...