The actress compared Sansa to Cersei Lannister (played by Lena Headey) admitting that she will do anything to protect her family
In a new interview, she teased an evil streak within the flame-haired heroine and hinted that her relationship with Jon Snow (Kit Harington) is fractured after he failed to thank her for saving him in the Battle of the Bastards.
Speaking about how Sansa is much-like Cersei, she explained: "They're both so family-obsessed and family-orientated, and will do anything for the people they love.
"I can totally see her becoming a Cersei and kind of driven mad by it, by the threats against her family. At the end of the day, that's why she does the things that she does, because she's terrified of losing the people she loves."
Game of Thrones: Sophie hinted that Sansa could become evil
Game of Thrones: Sansa is frustrated Jon doesn't recognise that she saved him on the battlefield
She's terrified of losing the people she loves
Sophie went on to tell Yahoo Lifestyle Singapore: "She'll stop at nothing to protect them. If that means becoming like a ruthless killer, leader, sadistic woman or evil lady, then so be it.
"I don't think it matters to her, and I can see Sansa swinging that way too."
Addressing the relationship between Sansa and Jon at the end of season six, the 21-year-old said: "I think she's frustrated – she's worked so hard, tirelessly to convince him that this is what the right battle plan was and he wouldn't listen to her.
"She ended up having to save him and yet he gets hailed as King of the North and he doesn't say a thing about Sansa saving him."
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Game of Thrones: Sansa and Jon's relationship has become fractured The cast of Game of Thrones in real life Wed, April 26, 2017
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Richard Brake as the Night King
Game of Thrones: The eighth season of the HBO series could be delayed until 2019
Sophie's comments come after it was reported that the final series of the HBO show could face serious delays.
According to the president of HBO, Game of Thrones season eight may not air until 2019 to ensure it goes out with a "monumental" finish.
"Yeah, [showrunners David Benioff and D. B. Weiss] have to write the episodes and figure out the production schedule," Casey Bloys told Entertainment Weekly.
"We'll have a better sense of that once they further into the writing."
Game of Thrones returns to HBO at 9pm in the US on July 16 and will be simulcast at 2am on Sky Atlantic in the UK.