Leonard realizes that Stephanie is cohabitation|living in his apartment and he wants to slow down their relationship after Penny points it out. Meanwhile, Sheldon is convinced that he has an untraceable disease and begs Stephanie to help diagnose him.
Stephanie is checking Sheldon's ears because Sheldon insists that he has some kind of inflammation in his ear, since he can hear a strange noise. Stephanie heads into bed first. Sheldon discusses The Roommate Agreement with Leonard. Sheldon claims that the Cohabitation Rider has been activated because Stephanie has been deemed "living" with Leonard, but Leonard denies that Stephanie lives at their apartment.
The next morning, Penny comes into their apartment in her underwear looking for coffee and meets Stephanie. An awkward conversation starts as Leonard tries to explain why Penny is there in her underwear and Penny is enjoying his faltering explanations. After Stephanie leaves for work, Sheldon mentions that Stephanie is "living" there now. Leonard continues to deny it. Penny then brings Leonard to his room and tries to prove Stephanie is living here. Even though the evidence mounts (her clothes and personal care items), Leonard continues denying it. When he discovers that Stephanie has thrown out his Bat Signal he realizes they are living together.
Later, Leonard comes into the cafeteria wearing his new uncomfortable pants that Stephanie bought for him. Leonard then announced to Howard and Raj that Stephanie was living with him. Howard states that this is a bad idea because Leonard will be unable to hit on other girls.
Meanwhile, Stephanie bumps into Sheldon at the hospital. Sheldon is convinced he has an illness and requests that Stephanie authorize numerous tests to satisfy Sheldon's hypochondria.
Leonard runs into Penny at the laundry room and asks if she had Fabric softener. Penny handed him her fabric softener and Leonard pours the whole bottle into the washing machine. Penny asked what he was washing; Leonard told her it was the pants that Stephanie got him. She pointed out that the pants will be ruined if he machine washed them. That was Leonard's intent. She then asks if Leonard was having problems with Stephanie. Leonard feels the relationship has moved too fast because of Stephanie moving in. Penny was able to convince Leonard to ask Stephanie to slow the relationship down.
Back at the apartment, Stephanie pretends that Sheldon's larynx was inflamed and he has to stop talking immediately. Sheldon is deceived and quietly obeys. Leonard arrived home and tried to explained to Stephanie how he wanted to take things slow, but they end up having sex before he is able to make his point.
Leonard runs into Penny again at the Laundry Room, she informs him that his pants are ruined. Leonard replied "good". She then asked how the talk with Stephanie went; Leonard told her it went well. Penny figured out he had sex with Stephanie and urged him to steer the relationship in the way he wants it. She was also amazed about how quickly Leonard had returned considering that they had sex.
The scene changes to Leonard and Stephanie who just finished having sex and Leonard tries to have the talk with her again. He leads with "I really like you" and Stephanie cuts him off and describes a terrible way that this may end up, while gradually tearing up. Seeing this display Leonard decides to not have the talk with her again.
The next day at the cafeteria, Leonard arrives with a hideous sweater that Stephanie bought for him. He then explained his problem with Stephanie to Howard and Raj. Then Howard suggested that Leonard tell her what he wants over a text message. Leonard accepts his suggestion and sends Stephanie a text, after that he says "I'm never having sex again". He gets a reply and says "I was wrong" and leaves Howard and Raj.
Finally Sheldon goes to Penny's apartment to get some herbal tea and honey from Penny using a voice generating software as he is still convinced he shouldn't talk because of the inflamed larynx that Stephanie intentionally diagnosed falsely. Sheldon misspells a word and asks Penny for some "heinie", meaning a bit of her rear-end. Sheldon does correct himself on the voice generating software to ask for honey.
- Guest starring:
- Teleplay: Bill Prady & Richard Rosenstock
- Story: Chuck Lorre & Steven Molaro
- "Despite some irritating moments I think this is a good character episode. Hmm. I think I do. There are decent jokes throughout and Leonard’s dilemma is relatable and enjoyable to watch. For now I will give the writers the benefit of the doubt." - The TV Critic's Review
- IMDb user reviews
- Title Reference: The name of the boys' third-floor neighbor (Mrs. Vartabedian) who's mentioned in passing during the episode.
- Chuck Lorre vanity card 
- This episode was watched by 10.8 million people with a rating of 3.9 (adults 18–49.)
- Episode transcript 
|Sheldon wears the Forks Distortion tee by Heavy Rotation (discontinued), the Antique Radios tee from TShirts.com , and a Captain Marvel shirt (Shazam!). Leonard wears an unidentified design featuring an olive green shirt with lighter green bubble graphics. The forks distortion design is a series of blivets, also called "devil's tuning forks" - two-dimensional objects which get interpreted by the brain as 3-dimensional, sometimes even after careful consideration and conscious recognition that it's only an optical illusion. Other examples of "impossible objects" include the Penrose triangle (featured on another of Sheldon's shirts, also by Heavy Rotation) and Penrose stairs, as well as the impossible cube (by artist M.C. Escher).|
- Stephanie was never mentioned after this episode. It was assumed after the text Leonard gave to her which Howard suggested that they broke up. No further information is available to what happened to her.
- Leonard says, "I initialed another clause naming you my sidekick in case I get superpowers." in the Roommate Agreement. Similarly, Howard and Raj argued over whom, among themselves, would be the sidekick if they had superpowers in "The Alien Parasite Hypothesis".
- Penny enjoys watching Leonard squirm while he explains her intimate appearance to his girlfriend.
- When Leonard is in the cafeteria with his bird sweater, it is seen that Howard's drink is rebranded as "Dr. Peeper", possibly an allusion to his personality.
- When Leonard and Penny are in the laundry room discussing Stephanie there is a continuity break in the filming. Penny is folding pink washcloths and is putting them on a pile. That pile is not growing properly.
- Goof: Why would Sheldon even consider putting clauses in the Roommate Agreement considering co-habitation when at other times early in the show, he barely even considered them having girlfriends?
- However, considering these kinds of seemingly farfetched questions is something lawyers do all the time when drawing up agreements. Considering how well versed Sheldon considers himself in legal matters, this can make sense.
- The relationship with Leonard and Stephanie in this episode foreshadows the major plot points of Leonard and Penny breaking up due to being at different places in the relationship and the tension of Sheldon and Amy's relationship as Amy was further ahead.
- Third episode of the "Dr. Stephanie" trilogy.
- S02E08: The Lizard-Spock Expansion - Howard tries to seduce Stephanie by showing her the Mars rover, however Stephanie ends up interesting in Leonard
- S02E09: The White Asparagus Triangulation - Sheldon worries that Leonard and Stephanie's relationship is not progressing well enough and goes to Penny, Raj, and Howard for advice on how to stop Stephanie inevitably ending the relationship with Leonard - Leonard and Stephanie are officially in a relationship by the end of this episode, in part, thanks to Sheldon
- S02E10: The Vartabedian Conundrum - Stephanie has moved into the apartment without Leonard even noticing; Leonard wants to slow things down with Stephanie.
- Sheldon: Good morning, Dr. Stephanie. I trust Leonard satisfied you sexually last night?
- Leonard: Oh, come on! Sheldon, we don’t ask questions like that.
- Sheldon: I heard you ask it over and over! How is it inappropriate for me to ask it once?
- Stephanie: He did very nicely.
- Sheldon: See? She’s not offended. And now you finally have an answer.
- Penny (entering): Out of coffee. Need coffee.
- Stephanie: Uh, hello.
- Penny: Hi! Stephanie, right?
- Stephanie: Uh-huh. And, and, and you are?
- Penny: I’m Penny, I live across the hall. I’ve heard a lot about you.
- Stephanie: Really?
- Penny: Mm-hmm.
- Stephanie: I haven’t heard a thing about you. Leonard? Why haven’t I heard a thing about this woman who lives across the hall and comes into your apartment in the morning in her underwear?
- Leonard: She’s heard about you because we’re, you know, involved and you haven’t heard about her because . . . I never slept with her, I swear!
- Penny: So, that’s Stephanie, huh?
- Leonard: Why do I feel like I’m the one that just got the prostate exam?
- Penny: You know, she seems very nice.
- Sheldon: Oh, she is. She’s terrific, and she’s proving to be a valuable roommate.
- Penny: Roommate? You guys are living together?
- Sheldon: Like hippies.
- Leonard: We’re not living together.
- Sheldon: Do I have to pull out the paperwork again?
- Leonard: We’re not living together.
- Penny: Are you sure?
- Leonard: How could I not be sure?
- Penny: Well, let’s find out.
- Leonard: Don’t you think if a woman was living with me I’d be the first one to know about it?
- Penny: Oh, sweetie, you’d be the last one to know about it. (Looking through his wardrobe) Hmm, cute dresses. I bet this looks great on you!
- Leonard: We’re not living together.
- Penny: Okay, hmm, scented candles, fuzzy slippers, ooh, floral bed sheets?
- Leonard: We’re not living together.
- Penny: Okay, moving on. Now, who are these guys at Disney World?
- Leonard: Uh, the big dog is Goofy, and the older couple with the mouse ears, I have no idea. We’re not living together!
- Penny: You’re going to go down swinging, huh? All right, well, we got your body lotion, your InStyle Magazine, your jewelry box.
- Leonard: We’re not… Where’s my Bat Signal?
- Penny: You have a Bat Signal?
- Leonard: I did. It was right here. She must’ve… Oh, my God, we’re living together.
- Penny: Really? What was your first clue?
- Howard: You know, if you can’t talk to her, why don’t you just text her?
- Leonard: Isn’t that kind of cowardly?
- Howard: Oh, yeah. It’s beyond contemptible.
- Raj: It’s true, but on the other hand you are wearing a bird sweater.
- Leonard: Sold. “I think it would be better for our relationship if you moved back to your place.” There. It’s done.
- Howard: Good for you.
- Leonard: Yeah, good for me. I’ll never have sex again. (Phone buzzes) I was wrong. See ya.
- Leonard: Look, I’m just saying, um, Penny is one of our many neighbours, you know, and in our building, neighbours come and go, it’s very casual, no dress code. In fact, some mornings I’ll just mosey down to the third floor in my pyjamas and have cereal with Mrs. Vartabedian.
Sheldon: Really? I have never once been invited to have cereal with Mrs. Vartabedian.
Leonard: She doesn't like you. (Turns to Stephanie) Um, well, uh, you have a gall bladder to remove and I have to get in the shower and Penny has clothes to put on, so...
Stephanie (to Penny): Well, it was very nice meeting you.
Penny (to Stephanie): Nice to finally meet you, too.
Stephanie (to Leonard): And I'll see you tonight?
Leonard: Okay. Bye-bye.
Sheldon: What could I possibly have done to offend Mrs. Vartabedian?