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.

Tropes in The Big Bang Theory Season One

• 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.
• Artistic License – Physics: While Sheldon is ill Leonard tells him to drink plenty of fluids, and Sheldon responds with "What else would I drink? Gases? Solids? Ionised plasma?". This implies that he doesn't think gases and plasma are fluids when in fact they are, because a fluid is defined as something which can flow. The state of matter that the joke relies on is properly known as liquid.
• 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.
• Entitled Bastard: Lampshaded in this exchange after Leonard and Sheldon's hilarious brawl, following Sheldon crashing Leonard's presentation in The Cooper-Hofstadter Polarization
  Sheldon: You could have offered me a ride home....
  Leonard: You're lucky I didn't run you over!
• Escort Distraction: In "The Peanut Reaction", Howard has to take Leonard out so the others can plan a birthday party for him. To do this, Howard fakes an allergic reaction so they have to go to the hospital, and when he can't hold Leonard away any longer, he incurs an actual allergic reaction by eating a candy bar with peanuts.
• 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: Leonard's instant crush on Penny.
• My God, What Have I Done?: Combined with What the Hell, Hero? in "The Jerusalem Duality". Leonard has given Dennis a very attractive girlfriend who has distracted Dennis from making great achievements in physics. Leonard feels terrible about what he did because now Dennis has become an unemployed young man with no career, no income and a drinking problem.
• Not Even Bothering with an Excuse:
  Sheldon: Sorry I'm late.
  Leonard: What happened?
  Sheldon: Nothing. I just really didn't want to come.
• Paintball Episode: "The Middle Earth Paradigm" begins with the guys coming back from a paintball game, covered head to toe in paint.
• 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 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 shortcomings aren'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.