Leonard's Opinion of PennyEdit
Leonard began liking Penny as soon as she moved in during the pilot. He began running errands for her, such as going to get a TV from her ex-boyfriend Kurt. It wasn't until he got the courage to ask her out that they began dating. They had a few fights but Leonard always liked her and they always managed to stay together. He was concerned about leaving her alone when he was arranged to go with the others to the North Pole. When he returned in Season 3 the first thing he did was go see Penny which she greeted with a kiss. He gave her a snow-flake which she loved and they began dating. Leonard was very happy with Penny and told her in "The Wheaton Recurrence" that he loved her, which surprised her. Later in the episode Will Wheaton breaks them up so his team could win a bowling match against Sheldon's team. Leonard was devastated by this and, as Sheldon pointed out, cried about it. He even sniffed the pillow she slept on and listened to depressing and romantic songs. In Season 4 he began dating Priya and she insisted that he stop talking to Penny and letting her over to their apartment. Even though he was dating Priya, Leonard was reluctant to stop talking to Penny but she agreed not to hang out with Leonard as much to help his relationship. At this point, Penny said goodbye to Leonard, though it didn't last. He has since broken up with Priya and gotten back together with Penny.
Penny's Opinion of LeonardEdit
When Penny first met Leonard, she only thought as him as a neighbor and a friend and had no romantic feelings for him at first. She asked favors of him and talked and visited him nearly every day. She ate take-outs with him and the others. Later on, she confessed she wanted to go out with a guy like him and with that, Leonard asked her out which she accepted. They went out a few times and fell out a lot. At the end of Season 2, the episode "The Monopolar Expedition", Leonard and the others were arranged to go to the North Pole for three months. In that episode, she gave him a blanket with sleeves and hugged him, which made Leonard concerned about leaving her, but when he asked her about it, she said it was just a going away present. After he left and she closed the door, she whispered, "It means I wish you weren't going." When he returned at the beginning of Season 3, he went to see Penny, which she greeted him with a passionate kiss. Leonard gave her a snowflake which she loved and they began going out again.
In the episode "The Wheaton Recurrence", Leonard told her he loved her, which suprised her because she wasn't ready for it, but they both got over it when they had to help Sheldon win a bet against Wil Wheaton in a bowling match. Wil Wheaton told Penny that it would be kinder to break-up with Leonard right away, which later revealed to be a trick to win the bet, but Penny had already broken up with Leonard, believing it would help him.
In Season 4, Priya wanted Leonard to stop hanging out so much with Penny. Penny agreed to it to help Leonard move on with his relationship. Penny hated Priya because of that and got upset with not talking to Leonard as much. At the end of Season 4, she admitted to Raj she regretted breaking up with Leonard. However, she is somewhat reluctant to start up a relationship with him again.
Penny and Leonard 2.0Edit
In "The Recombination Hypothesis", Leonard decided to ask Penny out on a date and envisioned a possible ending of that date. In his fantasy, things did not go well the second time around, but he decided to go ahead and ask her out anyway, and Penny agreed to go. The episode ended with Penny envisioning a shotgun wedding with her and Leonard, a possible reason for her reluctance to go out with him again and her need to pick up her birth control pills. Leonard and Penny's fantasies regarding their possible reconciliation proved to have their merits when in the following episode, #106, (Season 2 Episode 15), "The Beta Test Initiation", it was shown that the two were contemplating to be official again. However, to avoid the mistakes from their first time together, they decided to take things slow by treating the relationship as a beta test, and even went to the length of presenting each other Bug reports to settle any issues.
Things seemed to be going well by the end of the episode, with Penny kissing Leonard at his doorstep after their date and at the shooting range. In "The Friendship Contraction", it was apparent that the two are definitely in a relationship again, albeit them taking things slow this time around, and the beta test that was still very much going on. During a blackout at the apartment, Leonard opted to hang out with Penny at her apartment and the two were about to make out when Sheldon interrupted them.
In "The Launch Acceleration", Penny suggested that they move up their relationship and get intimate; however Leonard ruined the mood when he asked her to marry him in the middle of the intimacy. They later met and this time around, Penny did not run away like she did previously when he confessed his love for her, instead, she managed to muster up the courage to turn down his proposal and they remained dating. During "The Countdown Reflection", there was some friction between the two of them about the proposal, but when Howard was being launched they were holding hands to comfort each other.
In Season 6 Episode 1l "The Date Night Variable", Raj, who was lonely and wanted to go somewhere, butted into their date, insisted that Penny tell Leonard how she felt, but she was not ready and threw him out of the apartment. Leonard wants to talk to Penny about their relationship, but Penny says that she has had a hard day and wants to just hang. Penny is expressing doubts about her feelings for Leonard, though she claims to be happy with the relationship in "The Decoupling Fluctuation". She almost tells Leonard about her doubts and then ends up sleeping with him after looking into his sad eyes. In "The Higgs Boson Observation", Penny while spying with Amy sees Sheldon's pretty new assistant Alex Jenson flirting with Leonard who is not responding. Later when Sheldon and Alex enter the apartment, Penny tells her about Leonard and her five year experiment together (relationship) and then she leads him off to her apartment for sex. In the Halloween theme episode "The Holographic Excitation", Penny gets advice from Bernadette that you get out of a relationship what you put into it and that maybe Penny should get more interested in Leonard's work (it is also revealed that, up until this point, Penny's view of their relationship had been one-sided in her favour). She visits his lab and is wowed by his holographic images and says that she sometimes forgets how smart he is. Penny heats up their relationship by starting to engage in sex in different locations, twice in his lab and twice in the TARDIS photo booth at the Halloween party.
In the episode "The 43 Peculiarity", Penny is working on a class oral project with a British student, Cole, who makes Leonard jealous. Leonard follows Cole down the stairs warning him about Penny's boyfriend, the "gang leader". Penny witnesses his deception and gets mad at Leonard telling him that he has nothing to worry about because she chooses to be with him and that he knows that she loves him. This pronouncement shocks both of them since Penny has never told Leonard that she loves him and she runs off scared before she breaks into tears. At the same time, Sheldon's assistant Alex Jensen is starting to hit on Leonard though he doesn't recognize her intentions. In "The Egg Salad Equivalency", Alex asks Leonard out to dinner after he expresses an interest in the Physics lecture she is going to and this really startles Leonard. Though it makes him feel good "to the bones" to have an attractive young woman interested in him, he tells everyone he still loves Penny and wouldn't do anything about it. He mentions Alex's actions to Sheldon who tries to talk to her about it and lands the whole gang in the Human Relations Administrator's office. He also didn't tell Penny about and Alex's actions make her feel really insecure about their relationship. Leonard apologizes by showing up at her door playing a little ditty on his cello.
In "The Spoiler Alert Segmentation" Leonard suggests that he move in with Penny after he again gets exasperated with Sheldon. He asks her if she's all right with it, but she only agrees not to hurt his feelings and even tells Sheldon. She does try to get him admit that Sheldon can't get along without him. Amy plans to move in with Sheldon as roommates. When Amy confronts Penny since she can't move in with Sheldon, Leonard over hears the conversation. Penny tells him that he never asked her if she was ready. Then Amy and Penny go off to drink and talk about their jerky boyfriends and Leonard ends up back in apartment 4A. In "The Tangible Affection Proof", Leonard takes Penny out to dinner for Valentine's Day. Penny feels that all the efforts never meets the the expectations and she will end up disappointed. At dinner, Penny sees an old boyfriend proposing to the girl that broke them up. Leonard again tries to propose and Penny stops him. They begin to argue in front of Howard and Bernadette who have their own issues that night. Later after they barely say good night, Leonard tells Penny that she ruined the whole evening. Penny finally admits that she has commitment issues. She is so happy right now that she knows they are going to get married and since it is forever that scares her. Leonard then puts the responsibility of proposing on her and that she should do it when she's ready. In the end, she does ask him to be her valentine.