The long-wait is over, Warcraft lore fans! Turalyon and Alleria are quest NPCs in Argus. Turalyon appears during the quest: The Prophet’s Gambit at Krokuun (Argus).
Alleria Windrunner appears at Seat of Annihilation during the quest: A Strike at the Heart while fighting Aggonar (King of the Pits). If that name sounds familiar it is because he is the giant skeleton at the Pools of Aggonar in Hellfire Peninsula (Burning Crusade expansion). Aggonar stuns the player and Turalyon at 30% health, and Alleria leaps in to rescue her lover. Together, she helps to kill Aggonar.