Gwendoline Christie as Brienne. ''It would be a very obvious choice to be really ugly, massive: look like a man. I think it's a much more interesting perspective of society, and the narrowness of opinions, if it's a woman that just is not conventionally attractive. I felt that was a more interesting choice.'' Nevertheless, the role required her to challenge her perception of herself, her body and her image. She had to look credible as a warrior, swinging a sword and riding a horse. She worked with a strength and conditioning expert and put on 9½ kilograms of pure muscle. ''I wasn't someone that was physically fit, really, before,'' she says. ''I was committed to it. But there was certainly a lot of physical transformation. You're making yourself as unattractive as you possibly can do and that is quite difficult to deal with.'' Then there was the hair. It's a story she tells in most interviews, including this one - perhaps because it's a good story, but perhaps because she still struggles with it.

Maisie Williams as Arya Stark. ''They cut my hair off. I wanted that to happen, I knew that would happen and I wanted it to happen for the character, but that was bizarrely more difficult than I ever thought it was going to be.'' It happened one day, late in preparation for the role. Nikolaj Coster-Waldau as Jamie Lannister. ''I was a very good girl on set,'' she says. ''Went to my dialect session afterwards, after I'd had the whole thing chopped off. Went horse riding. Went back to the hotel. Cried for two hours. Called my mum. Yeah, came to terms with it, phh, three months ago.

''I don't know, so much of women's femininity is tied up with their hair. When you're very tall anyway and you have that taken away, it makes you feel a bit at sea.'' It was only the start of her coming to terms with the role. ''To have a part where so many of your personal insecurities are amplified, you're very unattractive and you're very masculine. It's incredibly challenging and it forces you to question your own notions of femininity - what it is to be a woman, in the part and outside of the part. ''It has been freeing. You find out more about yourself and that can be a great and reassuring thing and it can also be quite a disturbing one. It's been really liberating to play this part, and just empowering in every sense. But there's also a vulnerability there.'' It doesn't help that she is constantly reminded of her difference - both on-screen and between takes.

At the end of last season, and for much of this one, her character is paired with Jaime Lannister, an arrogant, blond, blue-eyed knight who is one of the few who can match her skills with a weapon. He starts the series as her prisoner, attacking her with his acrid wit. Jaime is played by Danish actor Nikolaj Coster-Waldau - to call him conventionally good looking would be like calling Mount Everest ''a bit of a climb''. And, for some reason, he has made it his mission to tease Christie about her looks, her build, her voice - anything, really. ''He torments me and really drives me to distraction,'' Christie says. ''The dynamic you see on-screen is almost identical to the one off-screen. I think it's just [what happens] when those sorts of people are put together for extended periods of time.'' Coster-Waldau doesn't deny he's provocative.

''She has a very … loud … laugh,'' he says drily when asked what it's like acting with Christie. ''She kind of allows me to torment her. I don't know why it happened. Well - I know why. She came on the show last season and for a long time all Jaime does with her is drive her crazy - and for some reason it kind of carried into our off-screen [relationship]. ''I was really being obnoxious to her all the time, then we would start shooting and we just carried on. She was game. I think she's really sick and tired of it now but I just can't stop, I'm just being horrible, saying really inappropriate things that I clearly wouldn't repeat here.'' In the end, Christie finds it useful. ''Sometimes as an actor it can serve you to assume a similar kind of relationship to that you have in the show. The fact that Nikolaj and I spar as we do, obviously it's beneficial.'' It's unclear how deeply the barbs sting, and how much of their relationship is play rather than real prickliness. But there are sore spots that genuinely sting when Coster-Waldau pokes them. Christie grew up in southern England and trained as a gymnast, but took up acting after a back injury. She graduated from Drama Centre London and has acted with the Royal Shakespeare Company - which is where the Game of Thrones casting director spotted her, and instantly recalled her later when he was asked to find a Brienne.

But as such a distinctive - let's face it, very tall and unusual-looking - actor, she has struggled to win conventional roles. ''It's been really hard,'' she says. ''It's disappointing because you realise that perhaps society isn't as imaginative as we might like it to be. But I'm not the only one. ''And,'' she says with an ironic wink, ''it's always fun to have a challenge isn't it?'' Game of Thrones is a godsend for unconventional actors, she says, mentioning Peter Dinklage, whose dwarfism was essential to the key role of Tyrion Lannister. ''The story is incredibly imaginative, which of course leads to imaginative casting - and the material that we all have is really juicy, so you get to see people being actors as opposed to being 'things', just physicalities.

''How brilliant to be involved in such a wildly successful, mainstream TV show that's breaking lots of boundaries.'' And despite Christie's insecurities, she loves playing Brienne. She loves a large woman playing a brilliant fighter (''I think it's quite sexy as well, actually - she can overpower a man''), and she loves the classic outsider playing the hero. ''Everybody experiences prejudice and many of us, or all of us, feel like outsiders at one time or another,'' she says. ''You see this person who's outside the conventions of society overcoming it in her own way and being brave enough to be unconventional, and I think that's quite exciting.'' But she hopes not to be typecast as the outsider her whole career. Christie was trained in the classical ''method'' school of acting - which is about transformation. In the future, she says, she hopes people can look past her frame, her build, even her gender. ''I'm interested in becoming, as closely as possible, a different person, a variety of different people,'' she says.

She doesn't want to be the tall actor, the tough actor, the ugly actor, the muscly actor. She doesn't want to be seen as an actor at all. She just wants to act. ''I don't really have any interest in playing the same part again and again,'' she says. ''Let's just keep everything crossed that doesn't happen.'' ■ Game of Thrones season three debuts on Foxtel on Monday, April 1. A beginner's guide to Game of Thrones The books American novelist and screenwriter George R.R.Martin began the Song of Ice and Fire series in 1996, and is now five books into a planned seven-volume series. They have sold millions of copies worldwide, having been praised for their gritty style, vast scope, huge cast of characters and intricate political shenanigans.

The TV series HBO bought the rights and put it in the hands of David Benioff (writer of the movie Troy) and sci-fi author Daniel ''D.B.'' Weiss. It was developed as ''The Sopranos in Middle Earth'', with a massive budget, filming in exotic locations such as Iceland, Morocco, Croatia and Malta. The world Westeros has a huge, frozen north, a big, muddy, forested middle dotted with towns and castles, a balmy south and some grim, rocky islands. The capital, King's Landing, is home to much of the political intrigue. Over the sea is a desert land of tribes and traders. The storylines

(Deep breath) The Starks, a noble family of northerners, are scattered across the world. One son is the head of a struggling rebellion, one daughter is captive to an enemy family. There are others. Up in the north, beyond a huge ice wall, a big army of wildlings is on the march, along with an even scarier bunch of icy zombies. Illegitimate Stark son Jon Snow is facing this. In the south the rich, ruthless Lannister family is scheming to take control of the kingdom, against a range of foes, with varying success. Dwarf son Tyrion Lannister lurches from triumph to disaster. Meanwhile over the sea, exiled princess Daenerys has hatched a brood of dragons and is plotting to conquer Westeros. And that's just a few of the threads. It's a hard show to jump into the middle of. Status quo At the end of last season, Theon Greyjoy has been kicked out of Winterfell, Robb Stark is married (thus breaking a promise to an ally), Arya is off to look for her family, Tyrion has lost power in King's Landing after its successful defence against Stannis, Sansa is still being hassled by Joffrey, Jaime is Brienne's prisoner (thanks to Catelyn Stark), Jon Snow and Ygritte have arrived at the wildling army camp, Daenerys' dragons have helped her escape Quarth, and a lot of ''white walkers'' are on the march in the north. New characters This season, keep an eye out for: