From Heroes Wiki
Piper is an evolved human who has been having terrible dreams, and is on the Company's radar.
Piper explains that she has been lacking energy lately because she has been kept up night after night by her dreams. After being visited in a dream by Sanjog Iyer, Piper remembers being held by the Company, and the experiments and testing they did to her. Left alone, she unnaturally stretches her leg to undo the latch on the table where she is bound. While escaping the laboratory, she meets a girl who introduces herself as Debbie, who was separated from Piper at birth. Piper fits her body through a very small window, leaving Debbie behind. Piper awakens in a fit and realizes that the events of her dream did in fact happen in her past.
Piper has the ability to stretch and deform her body in ways that would be impossible for a normal human being. She uses this power to undo a latch with her foot, and to slip out of a extremely small window.