Season three starts three months after the end of season two when the guys left for the North Pole.The third season saw the first appearances of future main cast members Melissa Rauch as Dr.
Penny throws herself at Leonard after he returns from three months at the North Pole and they begin a relationship that lasts most of the season, Penny and Sheldon start a quirky friendship though she can still annoy him, Wil Wheaton begins appearing as Sheldon's arch enemy, Howard begins to date Bernadette Rostenkowski and at the end of the season Sheldon meets Amy Farrah Fowler.
The men return home from their three-month expedition at the Magnetic North Pole (from the Season 2 finale), and Penny finally reveals her feelings for Leonard by kissing him as soon as he visits her.
Bernadette Rostenkowski in "The Creepy Candy Coating Corollary", and Mayim Bialik as Dr.
Amy Farrah Fowler in the season finale "The Lunar Excitation".
Feeling betrayed, Sheldon returns to his home in Galveston, Texas.
On Penny's advice, Leonard, Howard and Raj reluctantly go to Galveston to bring him back.