The Big Bang Theory / Season One
Returning home after a failed attempt to earn a little extra cash, Leonard and Sheldon find a new neighbor across the hall, Penny. Leonard decides to invite her over for lunch, beginning a close friendship between her and their other friends Raj and Howard. Leonard has an enormous crush on her, but through their interactions they slowly step outside their comfort zone.
- Above the Influence: Memorably in Leonard and Penny's first kiss, she was drunk and upset that she even invited Kurt to the party. Leonard knew the real reasons but couldn't take advantage of the situation.
- Characterization Marches On:
- Penny is not nearly as flighty and/or ditzy in later episodes as she was in the pilot.
- In the pilot, Leonard describes Sheldon as a pro in masturbating, something the asexual Sheldon as we know him nowadays is far from. (This is a carryover from the unaired pilot, wherein Sheldon has even had sex with a female colleague).
- Also on Sheldon, he was at first much wiser to relationships and social norms (though still awkward), traits that have been phased out in favor of EXTREME social ineptitude.
- Foreshadowing: Leonard obviously still had a big crush on Penny, but backed off on longing for her while she was dating a guy named Mike. When she kissed him on his birthday those feelings flared up again and lead directly into the season finale.
- Hell Is That Noise: Sheldon and Leonard's reaction to Penny's singing in "The Loobenfield Decay." (possibly Hilarious in Hindsight when you consider Sheldon begging Penny to sing when he is sick)
- Hopeless Suitor: Even Leonard considered himself this during season one.
- Love at First Sight
- Paintball Episode
- Polar Opposite Twins: Sheldon and his sister Missy.
- "The Reason You Suck" Speech: Penny tells Leonard he ought to grow up and stop playing with science fiction toys and action figures. After Leonard takes her words to heart and starts to sell his things, Sheldon later counters with Penny's own collections of Beanie Babies and Hello Kitty items.
- Leonard gives one to Katie in the unaired pilot, explaining that her short commings arn't because of her mother or the ex-boyfriend, but because she makes stupid choices and blames everyone else when she doesn't get her way.
- Recruited from the Gutter: In the original pilot Sheldon & Leonard take in a recently homeless woman and decide to reform her. She goes along with it mostly because she has nothing better going on in her life.