Lord Karl Heisenberg was a human mutant who lived in an Eastern European mountain range. A genius in engineering, he is assumedly the patriarch of the Heisenberg family. He runs the inherited Heisenberg Factory, located just outside the village, and serves Mother Miranda, along with the other three major houses in the mountain range.

Heisenberg was one of the children who was kidnapped and subjected to the Cadou parasite experiments by Mother Miranda, who brainwashed him into being her servant. Eventually, he, Alcina Dimitrescu, Donna Beneviento, and Salvatore Moreau became Miranda's lieutenants.

Among the Lords of the Four Houses, Heisenberg was the only one who held a grudge against Miranda, due to her own selfish desire to revive her late daughter and how he saw Miranda's family as nothing more than experiments. As such, he secretly planned a rebellion, hoping to use Rose's latent powers to defeat Miranda. At one point, he attempted to persuade Ethan to join him, but the latter refused upon Heisenberg revealing his plan to weaponize Rose.

The Heisenberg family was closely associated with the noble Beneviento, Moreau, and Dimitrescu families, and maintained an alliance with them in controlling the region. This control allowed the Heisenberg family to run their factory with barbarous cruelty, and according to sources, Heisenberg rarely strayed from it, preferring to hole himself up in its walls.