To fans of the show, it is not that surprising. Kelly’s Stamper has become a pillar of the show, even though in this fourth season, Stamper lives a bit on the margins, as Frank (Kevin Spacey) and Claire (Robin Wright) duke it out. But his story is, fans often tell me, what keeps them hooked on the show; all of the characters do awful things, but they feel for Stamper. I spoke to Kelly about his character’s charisma and foibles, as well as his own political leanings and whom he’s voting for this November.

I just watched you kill someone! 

[Laughs.]

I was just watching the season 3 finale, and it is a scary episode, and you are very scary in it.

He’s … a pretty scary dude, really. [Laughs.]

One of the reasons I wanted to talk to you is because a lot of people tell me that Doug Stamper is, for them, the emotional heart of the show.

I’ve heard that, but I’ve also heard other people say they can’t get enough of Frank, or they can’t get enough of Claire. It’s funny how everyone sort of has their own character that they identify with or that they love or whatever. It’s like any successful television show—take “Friends,” for instance, everybody had a different one that they loved.

How do you feel about Stamper?

I love him. [Laughs.] This is the greatest gift I’ve ever been given. I can remove myself while watching it—my wife and I love to watch the show together. When I’m watching him, it’s funny—it’s a big range of emotions. I respect the hell out of his work ethic. I find some of the things that he does despicable. But at his true core, I understand the guy. I’m not saying that I would do any of those things, but I understand him. And maybe that’s because I’m playing him, but I completely understand he’s a complicated guy, with that crazy, addictive personality that a lot of alcoholics have. And it applies to everything for him. That’s what makes him tick.

My editor Erin Keane has a theory that Stamper’s feelings for Frank Underwood are the only truly unconditional love in the series.

I completely agree. My wife and I finished [episode 7] last night and she turned to me and she’s like, “Jesus, you’re really the only one he can count on!” [Laughs.]

Why do you think Stamper is so loyal to Frank?

It’s a combination of a lot of things. To go back to talking about the addictive personality that’s in him: There was Rachel [Posner, played by Rachel Brosnahan]; he became obsessed and addicted to that. His job, though, too. He loves what he does, it’s what makes him tick. When we saw this failing character of Doug in season 3, you saw him be quote-unquote “happy,” you saw him living a pretty normal life. OK, you also saw a lot of crazy shit. But you saw him test those waters. What it’s like to have a normal relationship with a girl, what it’s like to have family involved in his life for the first time. What it’s like for him to consider taking a job that’s not going to be so taxing on him.

But it doesn’t make him tick. What makes him tick is what he does. It’s what makes him go and gets him up every day, and has him apply that insanely admirable work ethic. On some levels, I know he loves Frank. They’ve been together for a long time, they’ve come up together. So part of it is that. But part of, I think, his loyalty to Frank, on top of the love, is also a byproduct of his addiction to his job. And wanting to be the best he can be at his job. That’s what makes him drive.

In this fourth season, Stamper’s marginalized both by Claire’s manipulation and by her new hire, Leann, who behind-the-scenes you dubbed “Lady Stamper.” What was it like to be diminished in that way?

It was tough. Especially when Frank’s gone or is out of the picture for a while when he’s incapacitated. That was hell. I found myself like going to work and feeling—you know, I like everybody at work and I’m pretty sure everybody likes me. We have a great time there. But it was weird, because I did sort of feel outside the box of everything. For that period of time I felt lonely, isolated, while we were filming that. And it was bizarre. It was great for the character to fuel that, but it was very uncomfortable, to be honest.

And Claire! It’s like, come on! That’s the last person you want to go against. But then I thought, what I just saw last night [in episode 7]—I thought what was so interesting about what Beau [Willimon, showrunner] did is that even Doug knows that she is a formidable foe. She is not someone you want to mess with. But he has to. Even when he finally goes at her at Frank’s bedside, and says, “You left him.” You did this, you did this. She says, “Take it outside in the hall” and then she says something—I’ll paraphrase—like we need to work together now. I need you. We need to do this together. And he’s finally welcomed back in and everything’s going to be OK. And he’s like, no. I’m staying with Frank, that’s more important. I think the line is, “I’m staying with him.” And points a finger back at her, and put her back at odds with him. [Laughs.] I was like, This is crazy, Doug. But that’s why I think Beau is a genius. Those writers, you know?

I mean it’s crazy. When I first got this job, I didn’t know anybody, but I was like, wow. They’ve got a group of people here who—every single one of them I admire. Kevin Spacey, someone who I’ve looked up to. When I got the job I didn’t know how big of a character Stamper would become, certainly I never dreamed that. I was doing a lot of “Yes, sirs” and opening doors and whatnot, but I was like: I’m watching Kevin Spacey work every day. I’m gonna learn so much. [Laughs] That, to me, was so thrilling. And then everything that this has become has just been a great bonus on top of that.