Devon has appeared as a recurring major character throughout the first and second seasons, and began figuring more prominently toward the end of Season 2 as his suspicions grew, discovering Chuck's spy life in "Chuck Versus the Colonel," when he begins to provide cover for Chuck.

What episode does everyone find out about Chuck?

In “Chuck Versus the Subway”, late in season 3, she learns that Chuck is a spy. In the season 4 opener “Chuck Versus the Anniversary” it is revealed Ellie and Devon are expecting a baby.

What episode does awesome find out Chuck is the Intersect?

"Chuck Versus the Colonel" is the 21st episode of Chuck's second season, and the 34th episode overall.