Because of the DC Nation delay debacle, Young Justice's Before the Dawn was postponed until January... but iTunes didn't get the memo; and neither did a surprising DC character who made their animation debut in the episode. Spoiler images follow:
The mystery character is none other than Stephanie Brown AKA Spoiler AKA Robin AKA Batgirl AKA doesn't exist in the new 52. This was certainly a welcome surprise rife with potential for the upcoming, though delayed, back half of Young Justice Season 2. Even though Steph was a civilian in this episode, it seems her destiny will catch up with her sooner or later.