Just a couple months ago she was falling in love with a vampire. Now, she’s a 15-year-old looking to lose her V-card to a 20-something cafeteria worker.

But you’ve never seen Kristen Stewart like this. Portraying a teenager afflicted with a fatal neurovirus, Stewart plays with the physicality of her character who struggles to use every muscle in her body.

“I was obsessed with it three weeks prior to shooting and delved into it impulsively,” the delicate actress professes. “I couldn’t do it until we started shooting because it felt cheap. It felt like I was faking something.”

The Cake Eaters is a small-town drama centered around two families learning to deal with loss. Beagle (Aaron Stanford), his father (Bruce Dern) and brother (writer Jayce Bartok) are grieving the death of their mother and wife.

Georgia (Stewart) is a teenager coming to terms with the fact that death is creeping upon her. Determined not to let her illness stop her from living to her full potential, Georgia finds the beauty in life and love in Beagle.

“The one thing this movie has is an unabashedly outward sense of hope,” Stewart concedes. “It’s a very positive movie, which is very commendable since it’s about a girl who’s going to die before she reaches the age of normal consensual sex.”

The Cake Eaters releases in select theaters March 13.