You only arrived in the Glade that day and it turned out that you were the only girl. It's not yet clear to the Gladers that you are the key to getting out of the Maze. That day it was a bonfire and you were sitting near Minho, Thomas and Newt. They are talking about you, they don't notice that you're listening inconspicuously. You're just listening to Thomas speak...

Thomas: I think she could run fast, should we make her a runner?

Newt: he raises an eyebrow Are you sure about that?