Raf Stahelin

This article originally appeared in the June 2016 issue of SELF.

Sophie Turner is remarkably self-possessed. The 20-year-old has a fierce air of determination about her and a healthy dose of dry English wit—both of which she's going to need, because her star is about to explode. Not just thanks to Game of Thrones, HBO's dragon-scorched dark fantasy, on which she's been having a breakout sixth season. This summer, Turner also stars in X-Men: Apocalypse as Jean Grey, a teenage mutant with telekinetic powers; the trailer alone has already been viewed nearly 50 million times.

It's a big break that's been a long time coming; Turner has been gunning for this level of success since childhood. At 13, after a nationwide talent search canvassed her school in rural Warwickshire, England, she was cast as flame-haired Sansa Stark, the vulnerable daughter of a hunted family. Coming of age on-set "makes you grow up faster," says Turner. "But it also ignites that playfulness within you."

As Turner has matured, GoT fans have cheered, watching Sansa evolve from a people-pleasing damsel (forced to grovel before the fiancé who executed her father) into a coolly confident woman poised to escape her tormentors and reclaim her—and her family's—rightful power. "Sansa is really coming into her own now," says Turner. "It was nice to explore that."

Turner's own ambition first kicked into overdrive at age 11, when, on track to become a prima ballerina, she turned down a spot with London's prestigious Royal Ballet School in order to pursue her dream of acting. Still, the discipline and stamina ballet gave her came in handy as she prepared to play Grey on X-Men, alongside Jennifer Lawrence's Mystique. "I needed to get in shape—and quick!" says Turner.

Her 13-hour workdays included up to 60 minutes of exercise six times a week. "I never think of my days as long," Turner says. "I'd be in makeup from 5 a.m. until 7 a.m. But it was much crazier for the people who were blue!" Surprisingly, she found the role had more in common with Sansa Stark than just red hair (though, for the record, she's a natural blonde). "Both Jean and Sansa are strong characters with such great arcs," says Turner. "Neither starts out strong, but they find that power within them, whether literally or metaphorically."

Turner can relate. She may not be fleeing medieval sadists or Marvel villains, but she's faced her share of real-life challenges. "I found a lot of parallels between Jean and myself psychologically," she says. "Her journey is trying to figure out who she is, surviving the hormones and the boys, which are loaded on top of the fact that she's a superpowerful mutant. I haven't had that last bit to deal with! But I've had the challenge of growing up and having horrible skin and all the things that make you feel uncomfortable as a teenager, and knowing that everyone can see it—because 50 percent of them point it out to you."