Williams first joined the cast aged 12, when the show was far from the phenomenon it has since become. Now 17, she is just starting to come to terms with her fame.
"The success didn't happen overnight," she told the Radio 1 Breakfast Show. "It happened gradually, which was great for the younger members of the cast to get used to."
Game of Thrones is currently in its fourth season, with a fifth and sixth already commissioned.
"The viewing figures keep going up and up and people are catching up with the box sets now," Williams added. "It's really great, but also really daunting. During season one and two I didn't get recognised very much."
Williams kept future storylines secret but spoke out about her character, describing Ayra as a "sword-whipping bad ass" who is nothing like her.
"I'm not that cool but it's nice to pretend to be that cool," she said. "I have the whole world fooled."
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