It was arguably the twisted but fascinating relationship between Damian Lewis' "is-he-or-isn't- he-a-terrorist" Nicholas Brody and Claire Danes' brilliant bipolar CIA agent Carrie Mathison that kept audiences enthralled throughout the first two seasons of hit US drama Homeland.
But with Brody drug-addicted and AWOL in a Venezuelan slum throughout much of season three, it is the complex figure of acting CIA director Saul Berenson (played by Mandy Patinkin), who has become the main reason to watch in an otherwise uneven third season of the show.
The twists and turns of Berenson's working life and his equally complicated relationship with his wife Mira have formed the emotional heart of a season which has switched focus from Iraq and Afghanistan to the CIA's monitoring and surveillance of activities in Iran.
As a result, Patinkin has enjoyed a great deal of airtime in 2013 and he happily admits he's lapping it up.
"My biggest problem is when they say 'Fine, let's move on, we've got it'," Patinkin says, referring to Homeland's intensive shoots, which can take up to 12-14 hours per day.
"I'm heartbroken every time. I tend to get a lot of those three-to-four-day periods where it's all Saul stuff and it's walled back to back but I kind of like it that way. You have to just stay focused; it requires so much concentration and it moves so fast, so you don't get bored. You just have to stay on it. I hope it keeps me from getting Alzheimer's."
That's not likely any time soon. Patinkin is one of the entertainment industry's most intelligent and multi-talented figures. Apart from his CV in film and television, he has also built a long and esteemed Broadway musical career.
But he has also been called a prickly and difficult presence on a TV set. Patinkin won an Emmy for his role as Dr Jeffrey Geiger on Chicago Hope but then notoriously walked off the set of Criminal Minds, claiming it was too violent, and simply never returned.
That act of abdication put him in TV-land's black books for some time. But his incredibly rich and layered portrayal of Berenson, who manages to be simultaneously steely and ruthless but also soft-hearted and caring, seems to have redeemed him in the eyes of both his industry peers and legions of fans.
Patinkin says the key to Homeland's success is its atmosphere of deep-seated ambiguity. Those ambiguities are embedded across the board, from the Machiavellian plot twists to the shady, uncertain motives of many of its central characters. Is Brody "playing" Carrie? Is Saul a force of good or is he, as some fans and observers have suggested, a manipulator of the highest order? Is he willing to put Carrie through hell in order to keep a game in play?
"(Saul) will sacrifice anything to save Carrie Mathison because he believes that she is the gift to the salvation of the human race, essentially," Patinkin argues. "He believes that this young lady has a gift beyond anything he can understand. She looks at life out of the box. She is his teacher, so he will do anything to keep her in the game."
Beyond the conventional dramatic allure of red herrings, black operatives and good old-fashioned intelligence gathering, Patinkin believes the show is also successful because it bores deep down into the functioning of relationships, both familial and romantic. Carrie and Brody may have lured us in but family matters have kept us watching.
"I think it's hit a nerve with people and cultures and countries all over the world because of (the focus on) family," he says. "On the simple surface you have the father- daughter relationship (Saul and Carrie); then there's the Brody/daughter relationship, the Brody family, the family of the CIA, even the United States of America as a kind of family."
While Carrie's relationship with Brody is central to the show's storytelling, so too is her relationship with Saul, which is part paternal, part intellectual sparring partner. Out there in the real world, it turns out, Patinkin and Danes are close and mutually respectful friends.
"I have this wonderful relationship with her outside of work with her husband Hugh and their baby," he says.
"Professionally, it's one of the blessings of my life. She has taught me grace. We should be lucky to see her do endless things, because she really is magic."