Wendy S. is a meth-addicted street prostitute who provides sexual services in the parking lot of The Crossroads Motel, which also serves as her home. She has a son named Patrick, whose age is unknown. At certain points, she has associated with Jesse Pinkman.
After getting the false impression that Walt Jr. was using marijuna, Hank Schrader takes his nephew on a trip to the Crossroads Motel in order to scare him straight. There they encounter Wendy using a vending machine and Hank calls her over to Walt Jr. so that he can harass and question her to show Walt Jr. the harmful effects of drug use. Later she is seen in a motel room engaging in sexual activities with Jesse Pinkman.
After Walter White and Jesse Pinkman escape from Tuco Salamanca in the desert, Jesse hires Wendy to give him an alibi for the previous days: that they had not left the hotel for days, living off vending machine food. The two are picked up for questioning by the DEA and Hank Schrader interrogates both heavily to find more information on why Jesse's car was at Tuco's safehouse. Recognizing Hank from his earlier visit with Walter White Jr., she immediately stops talking, refusing to change her story or give Hank any additional information, stubbornly asking instead for a root beer. ("Bit by a Dead Bee")
Jesse later recruits her again, this time, to deliver poisoned hamburgers to the rival dealers who had killed Christian "Combo" Ortega, but fails as Walter warns Gus of the imminent threat on their lives. ("Half Measures")
Wendy appears willing to do anything to get her next fix, be it meth or root beer. While she may seem fragile, she has proven to be tough when she needs to be - whether it is defending the few standards she does have or covering for a well-paying "friend" (Jesse Pinkman) to protect his alibi. However, her lifestyle does appear to be taking a toll on her.