Querelian was an eladrin soldier from the Feywild.
He fought alongside his wife, Omaphara, against the werewolves during the War of the Pelt. Though he survived the war, his wife was slain battling the werewolf lord, Viktor Mazan. Querelian was furious when the Court of Stars sued for peace, believing that the werewolves should be exterminated. Swearing that he would make the werewolves pay for her death, he formulated a plan to murder Viktor Mazan and frame the eladrin city of Mithrendain, providing the spark that would reignite the war and see the werewolves destroyed.
His plans were ultimately undone by his wife's spirit, who had come to believe that while the war had been justified, restarting it would cause unnecessary bloodshed. Informing the Challengers of the Unspeakable about her husband's plan, she gave them her longsword, Moonclaw, and begged them to stop him.
Though Querelian had already sent ravens to Mithrendain calling for troops, the Challengers were able to defeat him and save Viktor Mazan before their arrival; once the adventurers explained the situation, Querelian was taken back to Mithrendain in chains. As a further sign of good faith, the Challengers also gave them Moonclaw.
The guards who arrested Querelian were employed by an eladrin named Dresyae, who was one of the city's council members. Dresyae sympathized with Querelian, and saw him as a potential ally in his bid to take over Mithrendain. In exchange for keeping Moonclaw for himself, Dresyae agreed to free Querelian to support him from the shadows.
At about the same time, Querelian received a letter from Tephra. Playing upon his hatred of both lycanthropes and mortals, and especially the Challengers of the Unspeakable, she enticed him to join her, "gifting" him with power in return. She sent an aberrant beetle that burrowed into the eladrin's flesh, feeding upon him and quickly multiplying into a massive swarm that devoured his body. His mind, however, merged with that of the beetles, transforming him into a kind of living swarm. Using his newfound powers of shapeshifting, he took on the form of an eladrin noblewoman named Jelvistra and began influencing the other council members to further Dresyae's plans, all the while planning on betraying Dresyae and taking Mithrendain for himself. He even corrupted Moonclaw, empowering it to slay non-aberrant creatures.
Ultimately, his plans were once again foiled by the Challengers of the Unspeakable, who had been hired by a suspicions council member to root out the corruption within their ranks. After a long battle, the Challengers killed all of the beetles that made up Querelian's swarm - leaving little more than a dessicated eladrin skeleton.