 A genuine romantic interest develops between Chuck and Sarah.Chuck's desire to maintain his close relationships and eventually return to a normal life is challenged by the dangers and growing responsibilities of his secret life, so that he gradually becomes a more competent, confident, and willing spy.In later seasons, upgrades to the Intersect would include skills in espionage as well as information (the reason the Intersect was originally conceived), giving Chuck temporary knowledge of hand-to-hand combat and other skills such as playing the guitar, using a zipline, foreign languages, dancing, and firearms training.