John Bradley's Sam Tarly proves a different kind of hero on HBO's 'Game of Thrones'

Samwell Tarly may not be your typical knight-on-horseback hero, but the stout academic has been as impressive as anyone in defending Westeros this season on HBO's Game of Thrones. 

Sam (John Bradley), poring over manuscripts at The Citadel, found records of a rich vein of dragonglass, a substance that can kill powerful White Walkers. The lowly maester-in-training also risked his life to save Ser Jorah Mormont from greyscale, allowing the wise military adviser another chance to help Daenerys Targaryen.

And, in Sunday's episode, Sam's partner Gilly, who helps him with his manuscript work, discovered a record of Rhaegar Targaryen's secret marriage, presumably to Lyanna Stark. That would make their son, Jon Snow (Kit Harington), an heir to the Iron Throne. 

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However, Sam, in his anger at archmaesters who refuse to respond to the White Walker threat, doesn't pick up on this huge revelation, which demonstrates he still has room to learn and grow.

"It's a huge year for Sam," Bradley tells USA TODAY. "Sam knows his physical limitations. He knows he's weak on the battlefield, that he can't use a sword, that he's not good on a horse. … But there's a lot of evidence to suggest he is brave and will do the right thing if he believes what's at stake is worth defending."

Sam has exhibited traditional chivalry, too, by rescuing Gilly (Hannah Murray) from evil Craster and killing a White Walker with dragonglass. The Citadel's archmaesters may have more book smarts, but Sam's real-life experience with White Walkers leaves him exasperated when his superiors decide against taking action.

"They decide it's not worth doing," Bradley says. "That really does make Sam snap."

The English actor, 28, enjoys his whirlwind ride on the international hit (Sunday, 9 ET/PT), after winning the role in his first audition after college.

"I wasn't even thinking about getting the job. I just wanted to do a good audition," he says.

As with many Thrones characters, Sam has changed dramatically over six seasons. At the beginning, he had been reviled and disinherited by his harsh warrior father Randyll Tarly, who sent him to the Night's Watch where he was mocked and abused. 

The Night's Watch bond formed with Jon, who stood up for Sam and made him a trusted adviser, helped Sam overcome the psychological scarring inflicted by his father. (Randyll and Sam's brother, Dickon, received a fatal comeuppance Sunday, courtesy of Dany's fire-breathing dragon.) 

That earlier connection now pushes Sam to leave The Citadel to find him, Bradley says. "The one place in this world where he did belong is by Jon Snow's side. He knows how important it is and how well they're going to work together."

Sam's relationship with Gilly and her son, named in honor of Sam, gives his life meaning, the actor says. "Before Sam met Gilly, he didn't think he had any reason to stay alive. As soon as he met Gilly and Sam came into his life, his project was to keep them safe. He had a role and a purpose." 

Sam may have a serious role in saving Westeros, but he's also been involved in Thrones' lighter moments. A montage of apprentice Sam serving gruel and cleaning chamber pots was an amusing (and nauseating) highlight of the sixth-season opener.

"I was pleased about that," he says. "Apart from being a funny moment, it (illustrated) Sam's psyche and motivation. He is deeply miserable and really degrading himself. … Because of rules and regulations, he's being kept from his purpose."

Sam emerged from that funk by breaking the rules, stealing keys to gain access to books that revealed the dragonglass mother lode and curing Mormont against the orders of Archmaester Ebrose (Jim Broadbent). He purloined more books before leaving The Citadel.

"Sam believes he has the right moral values. He's no longer slavishly obeying authority," Bradley says. "The only question he has left is: Is this the right thing to do?"