Kate Dickie, Aidan Gillen

[WARNING: The following contains spoilers from Sunday's Game of Thrones episode, "Mockingbird." If you haven't watched yet, it's best to sit this one out.]

Petyr "Littlefinger" Baelish finally had to lift a finger.

On Sunday's Game of Thrones, the wily political schemer killed a third person this season, but this time, he did the honors with his own bare hands. After his clingy wife Lysa (Kate Dickie), the Lady Regent of the Vale, flew into a jealous rage and threatened to throw Sansa Stark (Sophie Turner) to her death out of the Moon Door, Littlefinger (Aidan Gillen) intervened.

"My sweet silly wife, I have only loved one woman, only one my entire life," he told her. But just as she took this as a declaration of love, he clarified, "Your sister [Catelyn Stark]," before shoving her out the Moon Door so she could "fly."

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Littlefinger hasn't balked at the idea of killing people before. After all, he was behind the death of former Hand of the King John Arryn (Lysa's husband), the prostitute Ros (Esme Bianco), King Joffrey (Jack Gleeson) and poor drunkard Ser Dontos (Tony Way). This is the first time, however, that he actually got his own hands dirty.

"I guess the closest we got was when he pulled the dagger on Ned Stark (Sean Bean) in Season 1," Gillen tells TVGuide.com. "What was it about this one? It was just an inspired moment. There's also something else there though. It ties Sansa closer to him. She's there and she is a witness and she also has partaken in this in a way... They've got a secret."

Check out the rest of our interview with Gillen about Littlefinger, the most dangerous man in Westeros:

That declaration Littlefinger made is pretty intriguing. We assume he was just using Lysa for her title, but does he still have lingering feelings for the late Catelyn (Michelle Fairley)?
Aidan Gillen:
True love never dies. I mean, he does have quite a neck to even assume that Catelyn would have any feelings for the guy who shows up with Ned Stark's bones in a box as a gift. There's a certain amount of delusion there.

What is his obsession with Sansa? He's tried to get her to go with him several times already, but this time he succeeded. And he was caught kissing her...
I'd like to think there's a certain amount of good-heartedness in there. Her being Catelyn's daughter, obviously I'd want to look out for her. But [there are] other self-serving reasons as well.

Does he want her as a political pawn or does some of it have to do with Catelyn?
For sure, and I think Sansa views him as a political pawn too. Or she's probably not thinking politically, but she's playing him. She's becoming something, she's changing. And I think it wouldn't be beyond her to be playing me.

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Does he think of himself as Sansa's mentor? Or perhaps a father figure?
I think kind of a mentor. I think we're also going to see that with Lysa's son Robin Arryn (Lino Facioli) as well. These two young people need some guidance, and I do put myself in that position. I traveled to the Eyrie with Sansa. She assumes this identity, this alias Alayne Stone. She likes it, she likes role playing. It's more like a surrogate avuncular uncle-like relationship. I think a lot of this stuff is complicated.

Has Littlefinger actually helped her to play the game better?
I think so, yeah. It's quite interesting to see someone else get clever like that. I think she can be surprising. I don't really know what's going to happen with Robin yet either but you can see that there's some of that guidance maybe going to come into play there. And I'd like to think a softer side and that there is somebody in there who is genuinely sweet you know?

Let's not forget that he was the mastermind behind Joffrey's death, not poor Tyrion. Why did Littlefinger want Joffrey dead?
Joffrey was unstable and already a fascist dictator. Where would we be in 15 or 10 or five years' time? He was just too dangerous.

So he had Joffrey killed as a public service?
Not really for the good of the realm. Not just for himself. With a facist dictator in power, it's not very chaotic. He thrives on chaos. And we all don't know where this ends either. So there's a certain amount of projection I can do about where it's going, but the final two books haven't been written yet, which is one of the most exciting things about it actually.

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And was killing Ser Dontos just collateral damage for him?
No. I mean I think the line is, "I wouldn't trust a drunk fool." He's untrustworthy. If I could buy him, somebody else could buy him too and probably will. So that's just the way it goes.

What drives Littlefinger? Why do you think he's so ambitious? He's been such a stealth player up until now.
Rejection and desire. Humiliation early on, very early on. And not just from being a poor kid from the back of beyond, which is what he is, but you know he's been unlucky in love. So,  there is something of that in there. It's not really that apparent. It should be apparent that he's been rejected, if you like, by Cately Stark and humiliated then by Brandon Stark and slit from navel to here. I do have a scar there you saw somewhere in season 1.

It's not just that, but being put down and humiliated by people generally. I don't think it's a quest for absolute power. That's not the drive. It's just to put yourself in a position where people are not going to humiliate you again. He's not totally defensive. There's a lot of glee actually in playing the game the way he's playing it. It's very satisfying to see your longterm plans come to fruition. He's one of the smartest guys in the land. His plans are very well laid, and he sees way further ahead than a lot of other characters, so there's an amount of actually enjoying the game. I don't think it's coincidental that he used the term "chaos is a ladder." We've seen that as the kingdoms become more unstable in the wake of the Red Wedding or some other stuff that comes up, he is calmer and calmer.

We have to ask: We've heard you speak normally (like on The Wire), but where did you get Littlefinger's dramatic whisper/hoarse growl from? What did you try to infuse into this characterization?
This could be categorized loosely as a fantasy series, very loosely. It's not set in the past. It's not set in medieval England or whatever, but my own accent is a bit modern ... I think what I was going for was a kind of patriarchal thing that something like John Huston had in China Town. I'm not saying that's what I got or that I was trying to pull it off or I did pull it off. It's just something different. There is something about that character that you want people to tell you things. You want to be able to make people feel relaxed or comforted or scared or whatever so you want to have some kind of a voice where you can achieve these different ends with.

What do you think of Littlefinger? How far will his ambition take him? Wasn't Lysa's death satisfying?

Game of Thrones airs Sundays at 9/8c on HBO. Check out the cast discussing the best and worst hair on the show below:

(Additional reporting by Sadie Gennis.)