Jessica Jones star David Tennant was unsurprisingly cagey when pressed for details on how his new Netflix show may or may not connect to the larger Marvel Cinematic Universe. “For the rest of the evening tonight, I’ll be thinking, Should I have mentioned that? Am I in trouble now?”

Like any actor in a Marvel project, he’s been well trained to be vague on the details, but this isn’t new territory for the Scottish actor, who spent four and a half years carefully guarding secrets from enthusiastic Doctor Who fans. “I couldn’t have had better training for it by doing Doctor Who,” he says. “Any of these worlds where there’s an enthusiasm from the people who enjoy the shows means that secrets are prone to leak. I think it just means you have to be that bit more careful about protecting the surprises, because drama without surprise is . . . particularly in this kind of drama, doesn't really work.”

And speaking of surprise: in Jessica Jones, Doctor Who’s goofy, clean-cut “skinny boy” has traded in his trademark tight, blue and brown suits for a scruffy chin and purple threads to play Kilgrave, a.k.a. Purple Man, one of Marvel’s most nefarious villains. The Netflix series—based loosely on the comic book Alias by Brian Michael Bendis—tells the story of Jones (Krysten Ritter), a former superhero licking her wounds, recovering from trauma, and hiding out from the world in the slums of Hell’s Kitchen. The inflictor of that trauma? Kilgrave. And as the series kicks off he’s back from the dead to torment Jessica once again.

This isn’t the first time the beloved actor has gone dark. Doctor Who fans have seen him play a tormented Hamlet, a manipulative cabinet minister in The Politician’s Husband, and a damaged detective in Broadchurch. But they’ve never seen him quite like this. “I think there’s something rather chilling about him,” Tennant says. “He’s not particularly interested in world domination, or accruing vast amounts of wealth, or destroying the Fantastic Four, or whatever it might be. He’s just out to get what he can and he has this extraordinary ability which means that he has a certain indestructibility, really.”

But Tennant also acknowledges that Kilgrave’s powers of total control over others—which he often uses to inveigle young women or get a seat at his favorite restaurant—are scary because they come with a “certain wish fulfillment” that makes him “horribly appealing.” Having people obey your every command? “Of course, that’s something that we all slightly, perhaps at times, start to fantasize about,” Tennant admits. “Maybe that’s why he’s particularly terrifying to people.”

Jessica Jones is essentially a 13-episode metaphor about sexual assault and survival; like Netflix’s other Marvel series, Daredevil, it is steeped in reality. But like Vincent D’Onofrio in Daredevil before him, Tennant manages to bring some degree of humanity and sympathy to his monstrous role. Tennant’s extreme likability works to his advantage there. “At first he comes off as all bad, and he pretty much is, but you can at least understand some of the reasons why he might be. He’s more interesting than just a mustache-twirling villain,” Tennant says. “I think there are—how do you call it—clutches of contradictions in Kilgrave’s character.”

Marvel's Jessica Jones Courtesy of Netflix

Netflix and Marvel’s commitment to realism also meant a major change for Kilgrave, whose skin is purple in the comics but is completely Tennant-colored in the show. “There’s a difference to creating things on a two-dimensional page and creating them in a three-dimensional, living art form,” Tennant explains. “You have to always be aware of what looks extraordinary and what might just look a bit silly or screwy.” Are there lost makeup tests of Tennant in full purple-face? “It was never tried. I’m slightly disappointed. Although, I’m sure by week two turning up at five A.M. to be slathered in purple paint would’ve become rather harsh.”