A traumatised Starfleet soldier among the defenders of AR-558, who refuses to let Julian Bashir change a filthy bandage because it was applied by a comrade who was killed moments later.
Vargas appears in The Siege of AR-558, played by Raymond Cruz.
By 2375 he has spent five months defending a captured Dominion communications array against repeated Jem'Hadar attacks and hidden mines, far beyond the period Starfleet rules allow before rotation. He is jumpy and close to collapse, and almost fires on Sisko's party when it arrives.
Bashir notices the dirty dressing on his arm, but Vargas will not have it touched. He explains that it was put on by a fellow soldier named McGreevey, a man he could not stand because he never stopped talking, and who was killed while tying it. Vargas fights in the last battle for the position and is stabbed in the back by a Jem'Hadar soldier.