Larry is a complex man, crammed with quirks, such as his predilection for white food, but often serves as the counterweight to Don's pragmatism, reminding Charlie of the need to broaden his scope of inquiry, and look beyond the immediate, and obviously necessitous. Larry spends the time from the end of "Killer Chat" to "The Art of Reckoning" ticking a big item off his bucket list - in space.
Larry is a cosmologist by profession, and teaching load, but like Charlie is endlessly intrigued by life in all its permutations, and frequently offers essential insight, or a vital moment of refocus. Larry holds a doctorate (or more), and is a professor at CalSci, having (a baker's dozen years before the series starts) been Charlie's instructor when the only just teenage Mr. Eppes graduated from high school, and set foot on campus. Unlike many in his position, Larry never seems remotely threatened by the fact that, in certain areas at least, his former pupil has outstripped him.
Larry is the holder of the "Walter T. Merrick Chair in Theoretical Physics" at CalSci, as he states in "Disturbed". When Alan decides to go 'back to school', he finds Larry a very useful sounding board, as well as a companion whose interests do not automatically end in beer.