ST:DS9, Captive Pursuit, Episode 106
Not a bad episode. First new alien species come through the wormhole, come to find out their culture is centered around the hunting of a "lesser" race bred and trained for the hunt itself. Of course, O'Brien befriends the hunted alien immediately, and conflict ensues.
Quark continues to be the star of the show so far, but Odo's in close second. Good development of O'Brien and Sisko's relationship, in that Sisko is alright with yelling at O'Brien because the coffee from the replicators is shit, but they exchange a knowing wink when they conveniently brush aside the Prime Directive.
Some things never change, Trek.