At the start of Mass Effect 3, James Vega comes to collect you for a meeting with the higher ups. The conversation between you implies that there is history, but I don't recall ever encountering him.
The wiki on him states:
[James] had taken up residence in Omega playing cards in bars. During a game, a broadcast regarding Commander Shepard's actions during the events of Arrival and the galaxy's reactions aired on a nearby vidscreen.
Arrival was one of the few DLCs I didn't play for Mass Effect 2, did I miss his introduction there?