Doctor, Surgical Resident
Leonard Hofstadter (ex-boyfriend)
Stephanie makes her debut in "The Lizard-Spock Expansion" (S02E08) where Howard tries to seduce her by taking her to a Jet Propulsion Laboratory and letting her drive a Mars rover. But when he sticks the robotic car in a ditch, he calls his friends over for help and asks Leonard to drive Stephanie home. This proves to be lethal for Howard's chances with Stephanie, as she and Leonard end up making out in the car. She eventually confesses to Howard how she's interested in Leonard and not him, which Howard takes as Leonard's betrayal of his trust. Howard starts acting like Leonard to be dead to him. However, he forgives Leonard and Stephanie when Stephanie sets him up with her roommate Lisa.
Stephanie continues dating Leonard in "The White Asparagus Triangulation" (S02E09), which leads to several encounters between her and Sheldon. Although she seems to put up with Sheldon's obnoxiousness, she uses her cunning to keep him under control. For instance, she makes him believe he has to stop talking because of his inflamed larynx in "The Vartabedian Conundrum" (S02E10), which keeps Sheldon mute until the end of the episode.
By "The Vartabedian Conundrum", she has established herself in Leonard's apartment , which leads to Sheldon and Penny pointing out that he and Stephanie are living together. Leonard finds that his closet is full of her clothes and her jewelry box is on his dresser replacing his Bat-signal. He realizes that the relationship is moving too quickly for him so he insists she re-locate to her own apartment. He does, however, have trouble shaking her off, since when he tries to talk to her, she makes sexual advances on him and the two end up having sex. Stephanie seems to be insecure in her relationships and counters with being very aggressive sexually.
Although it's not seen on camera, it is known that some time between "The Vartabedian Conundrum" and the following episode "The Bath Item Gift Hypothesis" (S02E11), that she and Leonard broke up, but it is unknown who caused the break up and why. Leonard is seen texting her supposedly asking her to move out. It is also unknown what has become of her and if she and Leonard continue to be friends.
Main article: Leonard and Stephanie
Stephanie's primary role in the show is being Leonard's girlfriend. They met in "The Lizard-Spock Expansion" , and continue dating for two additional episodes. Eventually it seems they broke up, but it is unknown why and when though Leonard thought their relationship was moving too fast after he realized that she had moved in with him.
- Stephanie did her medical internship at Lawrence Memorial (fictional) in Galveston, Texas, which is where Sheldon was born.
- Of all of Leonard's exes (Joyce Kim, Priya Koothrappali, Leslie Winkle and Penny), she is mentioned the fewest amount of times by the cast.
- Stephanie was mentioned only one time since her breakup with Leonard in "The Apology Insufficiency", when Sheldon mentions that Howard got the Mars rover stuck to impress her. It should also be noted that Sheldon didn't even refer to her by name.
- Stephanie is the only girlfriend of Leonard's who Sheldon really liked. Later Sheldon did admit that he liked Penny.