Lewis is one of the four Intersect candidates chosen by Langley, after drawing from a psych profile Chuck created based on his own personality. Lewis was a star hacker by the age of 14; and a tech ops specialist, an elite bomb specialist. Notably, at least for Chuck and Morgan, his Warcraft guild took down Deathwing world first. After a four month exchange program in the UK he now affects an English accent. He was Chuck's second choice for the new Intersect.
During testing, he fails Morgan's assessment by naming Caress of Steel as Rush's best album. He responded to Sarah's question about conflict by saying conflict could be avoided simply by being civil. He tried nun-chucks against Casey in a weapons test and took a boot to the face.
When Casey disarmed the recruits after a murder in Castle, he had to be told to remove the one 'in his skivvies.' Casey said that he didn't trust an American operative with a British accent.
During the murder investigation, Sarah and Casey make the assumption that Lewis, the bomb expert, was the killer, and Chuck went with the conclusion until the discovery of Lewis' garroted corpse stuffed into the ceiling.
Chuck ultimately did deduce who the murderer was, only to be shocked to discover the target had been him, Lewis and Brody were merely collateral damage.