[Warning: This story contains spoilers for episode five of Game of Thrones' sixth season, "The Door."]

If there's one word that's synonymous with Game of Thrones, it's this: "Hodor."

The word, previously a rallying cry for fans of the Emmy-winning fantasy series, now carries new meaning following the brutal events of this past Sunday's episode, "The Door." At the end of the hour, friendly giant Hodor (Kristian Nairn) gave his life to protect Bran Stark (Isaac Hempstead Wright) from nightmarish monsters. In the same breath, however, viewers learned that Bran's magical ability to travel back in time and "warg" into others — Hodor specifically — turned the adolescent version of House Stark's kind-hearted protector into the man we know today, an unintended side effect of Bran's trip back to the past.

The revelation that "Hodor" was a mangled version of "hold the door," thanks to a time-displaced Bran, stands out as one of the most mind-bending and devastating twists in the entire series. And right at the heart of it stands Kristian Nairn, the Northern Ireland actor who's played Hodor from the very beginning of Thrones.

Nairn spoke with The Hollywood Reporter about his fan-favorite character's brutal demise, the ramifications of Hodor's death and more.

How did you find out about Hodor's death?

It didn't come from [showrunners David Benioff and Dan Weiss] directly. It came from my gossiping friends, who will remain nameless. (Laughs) We obviously talk about our scripts among us actors. We don't always get scripts at the same time. I remember talking to another cast member and saying, jokingly, "So, do I die this season?" And that cast member had a look of panic, like, "Yep! You're dying, and I don't know how to tell you!" That's how I found out. A couple of days after that, I got the call from David and Dan: "Sorry to tell you, but yeah, the journey ends here." They said it was going to be a good sendoff. I never dreamed it was going to be that good.

What was your reaction when you learned how Hodor's death would play out?

I actually cried. I didn't cry openly, but I had a little bit of a sob to myself. It's just so sad. To me, it's very satisfying as well. It ties up a lot about Hodor. It ties him all together and kills him at the same time. It's very Game of Thrones. (Laughs) It gives you something you want with one hand, then cuts your hand off with the other one.

When you found out what "Hodor" means, did it line up with how you had been interpreting the word throughout your run on the show?

I had no idea. I really hadn't a clue. I hadn't thought about it too much. I always viewed it almost as just an expression. I didn't think it was anything too significant, really, but I was wrong. All my theories were wrong — completely wrong, I'm glad to say! This was completely off the mark. That's part of the fun, as well. There are so many theories of it, ever since Wylis appeared in episode two. People have been going crazy with theories. Some people were getting quite close, actually.

There's a great story making the rounds this week about a fan who confronted George R.R. Martin about the meaning of Hodor, correctly guessing it meant: "Hold the door." Apparently, George laughed at him: "You have no idea how close you are!"

Yeah! But you know what? I've heard literally 200 different theories. Someone's bound to get it. I'm sure people have guessed the ending as well. I'm sure people have guessed correctly everything. Look at Facebook, and you'll see someone with an interpretation of some plot, and someone is bound to get it right sometime.

In your mind, how much did Hodor know about the fate he was driving toward?

I kind of think when this all happened to Hodor as a child, he had almost a soft reset in his head. I don't think he really recognized Bran when he saw him again. I don't think there was any connection there. I think when he saw him in the present day, he saw him as for the first time. I don't think he was aware of what was coming for him. Not at all. I think there was a bit of a reset there, a short circuit. After that, he was a physically different person. His personality was altered, he had to learn how to communicate again — whether successfully or unsuccessfully. That's the beauty of it, too. There's a lot of room for interpretation here, and we'll be asking questions for the next…well, forever.

How did you play Hodor's final moments? Some are wondering how much Bran is in there versus Hodor.

It wasn't Bran. He only gave him almost like you would slap a horse at the start of the race — a giddy-up to get him up and going. I don't think Bran would be able to do the warging thing from the situation he was in. But also remember, it wasn't Bran who told Hodor to hold the door. It was Meera. Hodor was acting under the instruction of Meera, to the start. He was terrified running down that tunnel. If he was warged, he wouldn't have been terrified. I think he realized the only way Bran and Meera could be safe was for him to be sacrificed. I don't think he was happy about it, but…

In that moment, does he have a feeling of fulfilling a destiny?

Maybe. Maybe. I think there's a bit of sadness as well, when he sees them disappear into the snow. I think he realized, "That's it." He's never going to see them again. I think, really, Bran represented home for Hodor. He represented Winterfell. That's one of the reasons Hodor was so attached to Bran. And he liked Meera, too. I love that scene where they're talking about bacon and sausages; that's a beautiful little scene. I think he was happy that he could help. As a server, he was always happy that he could help…which is so unlike me. (Laughs) There's a whole lot of acting going on there.

When Bran sees Wylis shaking on the ground saying, "Hold the door," there's this mounting horror on Bran's face. Do you see this as an accident on Bran's part, or is he willingly allowing this to happen?

Bran is very behind on his studies with the Raven. He has no idea what he's just done. The last thing he did was to accidentally shout at his father, and perhaps his father heard him. That's as far as he's delved into this. He doesn't know that he can warg in the past. He doesn't know he can affect people there. Circuits are being crossed. It's like having a crossed wire on a telephone. He doesn't know the results of this. He starts to realize, though, that this is due to him. He sees the white eyes, and he's wondering how Wylis can see him, and then he starts to realize he's caused the short circuit.

Interesting way to describe it, too, because Hodor is a character where signals are crossed sometimes, and it's not always clear what Hodor means and what he wants. For that to be at the heart of transforming that character, and ending that character…

Yeah. Yeah, it's almost come full circle there.

What does Hodor's death mean for the show's tone?

It's a great move. It's bold and genius. I believe this is directly from George and the books. I don't think this is an excess, extra death for the show. It's just really good storytelling. It's absolutely genius. It's the death of innocence. Hodor, in many ways…I wouldn't say he's the moral compass, because I think he needs more than one word to be a moral compass, but he was definitely a heart. There was a sense of warmth and humanity in him. That's now been murdered. I think it had to happen, in a way, for Bran to progress. He needs to realize how important he is. I understand that Bran's a bored teenager. His life has been ruined. But whether it's been done to him or not, he now needs to know the gravitas of what's happening and how he can affect the world. I think it's going to hit home for him. In this one episode, the Raven has died, his direwolf has died, and Hodor has died. He pretty much wiped out an entire race of tree people, too, just by being bored!

It's a hard lesson to learn, but hopefully he learns it at least.

I think he will. I think he will. But after a year of not saying anything, and being so careful about what I say, I'm in a joyful situation now. I haven't a clue what's going to happen next, so I can just let it all go. I don't have a clue. (Laughs) I can't wait to watch it as a viewer and not have people hanging onto every word I say: "Spoilers! Spoilers!" I just don't know anymore!

Have you held the door for anyone in the past few months?

Not yet. Too soon. (Laughs) But I've seen this on Facebook, that people are sticking my face onto elevator doors, by the "Hold Door" button. It's pretty good.

Does the word "Hodor" take new meaning now? It was a rallying call for so many fans of the show. Does it carry a darker connotation after Hodor's death?

I think now it has nostalgia. Of all the meanings it's had in the past…it's meant so many things to Hodor, and so many things to everybody else. Now, knowing what it means for real, I think people will hold onto Hodor as a multi-function word. I certainly will still use it that way.

A lot of people have discussed Hodor's death as heartbreaking, devastating, bold. He was a man of limited vocabulary, but you have more words at your disposal. What's the word you would use to describe the death?

I think…I think "heroic." I like that one. Because not all heroes hold weapons. Some hold doors.

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