Sheldon tells Penny he is uncomfortable with Leonard dating his arch enemy Leslie, but on Penny's advice he accepts the relationship.
Season two starts immediately after the end of season one with Leonard and Penny's date.
Jim Parsons submitted the episode "The Bath Item Gift Hypothesis" for consideration due to his nomination for the Primetime Emmy Award for Outstanding Lead Actor in a Comedy Series at the 61st Primetime Emmy Awards.
Season two begins to deal with character development, including Sheldon becoming more and more obsessive.
Leonard and Penny's relationship takes a turn for the worse when they break up, but this is quickly resolved.
After the guys return from a Renaissance fair and see Penny with her new boyfriend Eric, Leonard is approached in the Caltech canteen by Leslie Winkle, who proposes renewing their one-time "relationship".
As she has grown out of one-night stands she suggests they take it slowly, first determining their compatibility on all levels before proceeding to full sex (if at all); Leonard can assume the "male role".Penny, frustrated at making no progress in her acting career and not having had sex for six months, becomes curious on seeing Sheldon play Age of Conan.He helps Penny get started; she buys the game and soon succumbs to video game addiction, annoying Sheldon by persistently asking him for game tips night and day.After listening to Leslie in the Caltech canteen, Sheldon is convinced that Penny needs to have sex to relieve her stress and restore her regular life.Sheldon attempts to fix Penny a date with the aid of an online dating service, but fails.Leslie expects Leonard to back her beliefs, but when he supports Sheldon, Leslie dumps Leonard, to Sheldon's relief.