Saoirse Ronan has always been one for mixing things up, whether she's playing ultimate bratty little sister in "Atonement" or snapping necks to a Chemical Brothers beat in "Hanna."

Ronan's latest project is a juicy one and suits the young actress perfectly. She's taking on the starring role of real-life feminist, pacifist and writer Vera Brittain in an adaptation of her memoir "Testament of Youth." "Harry Potter" producer David Heyman is working on the film, which is also being backed by the BBC.

The book details Brittain's experiences in World War I as a nurse and the losses she suffered, including her beloved fiancé Roland. "Testament of Youth" launched the young writer into the public eye; even Virginia Woolf was a fan of the book. Brittain's story was also turned into an award-winning TV mini-series in the '70s.

It's a great role for the grown-up actress, whose career hasn't followed the usual teen trajectory, but then again, not many teens snag an Oscar nom before they're allowed to drive. Meanwhile, she's got two hot properties in the can, "Byzantium" and "The Host."

In "Byzantium," Ronan costars with Bond girl and "Clash of the Titans" star Gemma Arterton as a mother-daughter team of vampires in the thriller directed by Neil Jordan. "Byzantium" was penned by Moira Buffini, the graphic novelist and writer behind 2011's "Jane Eyre" and the irrepressibly cool "Tamara Drewe." (YA fans should take note that Buffini is also writing an adaptation of "The Night Circus." Yay!) "The Host," of course, is a non-vampy Stephenie Meyer property. Ronan is currently gearing up for the Darren Aronofsky film, "Noah," which has a projected 2014 release date.

Right now, "Testament of Youth" is in the early development stages, so stay tuned to see what Saoirse Ronan has up her sleeve for us. And maybe someday soon we'll all learn how to spell her name without looking it up every time.

See Saoirse in 'The Host' Photos