Spoilers for Jessica Jones Season 2, Episode 6 and beyond. In the first season of Jessica Jones, our hero knew exactly who her nemesis was and what he looked like. Things get a little more twisted in Season 2, and like many Marvel Netflix shows, the real villains aren't revealed until midway through. Jessica Jones' Karl Malus is a Marvel comics villain, but his Season 2 arc barely scratches the surface of his comic book journey.
In Episode 7, looking like a rock and roll scientist straight out of an Iron Man movie, Karl assures Alissa that he is trustworthy — but as Jessica says, his experiments are performed when the subjects are not able to consent. The Netflix adaptation of this character seems to paint with a few more shades of gray. He's played by Callum Keith Rennie, who you may recognize from The Killing, The Man In The High Castle, and Battlestar Galactica. The character is in a romantic, but controlled, relationship with Jessica Jones' mother Alisa — something that the superhuman private detective is sickly familiar with.
While the Fantastic Four are one corner of the comics that the Marvel Cinematic Universe has not touched, on the page that's what got the fictional character interested in superhuman powers. Karl Malus' scientific pursuits turned illegal very, very quickly. He single-handedly ran the Institute for Supra-normality Research, and his seedy connections both funded his "research" and provided him with test subjects of the homo sapien variety. He also developed and sold chemical weapons before working with and actual "gifted" people.
He worked with a villain called the Fly, captured a heroic werewolf called Jack Russell and made him fight Spider-Woman, and basically experimented on anyone who came to him with mixed results. After serving some time in jail, he started working for a company called Power Broker Inc. that gave people superpowers, and while there he developed a drug that his patients grew dependent on — making them (and their powers) easy to control.
In a comic series called Superior Carnage, he was recruited by a villain — yes, Andy Serkis' character from Black Panther — to be on a team called the Frightful Four. Well, not so much recruited as merged with an alien called a Symbiote. His evil deeds in that story are a bit more extreme as an alien hybrid, but honestly not all that different. In that story he is finally taken down by Captain America, when Sam Wilson was wielding the shield, as well as Misty Knight.
Knight, as Marvel fans know, is a key character for both Luke Cage and Iron Fist on Netflix. Perhaps this means that Karl is a factor in other series. IGH seemed pretty legitimate, at least on the outside, but there are plenty of seedy underworld types in the Defenders world that would probably have loved to hire someone like him.
Karl looks different in the comics — with a cold white lab coat and a bowl cut instead of a ponytail and a series of graphic tees. He likes octopuses, which seems like an added detail for the show. Malus never had a love interest in the comics, if that's what you can call Alisa Jones. It's difficult to use this comic book history to pinpoint exactly what his motivation and endgame is, exactly. When Jessica finally finds him, he has her mother locked in the basement.
Rennie hasn't spoken about his surprise special guest star role — possibly because of the recognizable name from Marvel comics. It'll be interesting to see how they continue to adapt this character, and whether it means more Marvel characters will follow. Hopefully no aliens will get inside his brain.