Lilly is one of the 9 main characters of the show. She won't appear until around episode 4.

Lilly is fiercely loyal and optimistic. She is dedicated and talented. Overly ambitious she over-estimates her own abilities and often charges head first into trouble. She is proud and stubborn. She is personable and exudes warmth. Beneath it all she is torn between competing desires to do her duty and to have real human connection. Her warmth affords her momentary friendships but the nature of her work means she never lets anyone in close, except Wes. Those who are more intuitive can tell that her smile and sunny disposition hides a great deal of stress and pain waiting for peace and release.

A good character to emulate for this part would be Kaylee Frye from Firefly.