Louisville native Dan Nations and his friend Samson Cornette conceived of an adult cartoon, in the style of Adult Swim — the programming block on Cartoon Network that introduced late night audiences to “Aqua Teen Hunger Force” (2001), “Robot Chicken” (2005), and “Rick and Morty” (2013), among many others. Nations and Cornette envisioned a series informed by 1980s horror aesthetics and inspired by “The Addams Family” and “The Munsters.” But with blood.