Zariel

Zariel
Do not pity the fallen angel. Fallen angels survive the fall. How many other souls did Zariel bring down with her?
Zariel
Zariel rules Avernus, the first layer of the Nine Hells. Once a mighty angel charged with watching the tides of the Blood War, she succumbed to the plane's corrupting influence and fell from grace. She recently reclaimed her position as archdevil of Avernus after the cautious Bel proved inadequate at marshaling his forces to launch offensives against the encroaching demons. Now Bel advises her and helps her manage the war, though many whisper that her true agenda is vengeance against Asmodeus, and her true plan is to drive him from the Nine Hells.
All who enter and exit the Nine Hells must pass through Avernus, so the infernal armies muster on this layer. Here, the amnizus guard the citadels overlooking the River Styx, much of the fighting of the Blood War takes place, and devils gather to invade the Abyss. Anyone hoping to reach the lower layers must first contend with the darkness of this layer and the myriad threats it houses. Zariel manages it all and has the ultimate say over who comes and goes.
Given her role in the Blood War, Zariel is keenly interested in collecting souls from the greatest warriors on the Material Plane and securing their loyalty. She bargains hard, and mortals end up worse for dealing with her, because she holds all the cards. A bargain with Zariel is eternal; there is little hope of wriggling out of it.
However, she does expect the best from her servants, and so she allows her mortal followers to live out their lives, ever honing their talents, so she can put them to the best use when she finally calls in their debts. As a result, Zariel's servants are universally effective, disciplined, and dangerous.
Zariel's Lair
Zariel makes her lair in a basalt citadel that rises up in Avernus. From nearly a mile away, one can hear the screams and moans coming from the burned victims chained to the stronghold's wall, the dying remains of those who failed to impress the archdevil. The stronghold, covering five square miles, is surrounded by walls reinforced with high turrets. Devils of all kinds crawl over the structure, ensuring that no intruders breach their defenses.