Zariel

Zariel was once an angel, but her impetuous nature and love of battle led to her fall. In her previous life, she was charged with observing the battles on Avernus and tracking their progress. From this exposure, she grew obsessed with the Blood War, and a thirst for battle grew within her that she couldn’t ignore. In time, she became frustrated that she and the other angels were forced to remain spectators while the demons and devils battled. The hosts of Mount Celestia, she believed, could descend upon Avernus en masse and wipe both hordes of evil from the cosmos if they so desired. After her repeated requests to join the fray were denied, her frustration overtook her, and she launched herself into the Blood War. Accompanied by a mob of mortal followers, she cut a swath through a legion of devils before their numbers overwhelmed her. A delegation of bone devils later dispatched to the site by Asmodeus recovered her unconscious form beneath a small mountain of her slaughtered enemies. After allowing her to recover in the depths of Nessus, Asmodeus installed her on Avernus as his champion and new lord of that layer.

A Fighting General

When Zariel supplanted the pit fiend Bel as the ruler of Avernus, that change signaled a major shift in the devils’ tactics. Zariel’s fiery temperament and reckless maneuvering stand in stark contrast to Bel’s approach, which relied on his expertise in logistics and defensive tactics to make steady but slow advances. Bel remains one of her chief lieutenants, and he doesn’t discourage her reckless tactics in the hope that she will overextend her forces and suffer a defeat that leads to her removal.
For now, though, the devils are fighting with a berserker fury under her charge. Zariel leads their offensives herself, and her unyielding resolve coupled with the fighting skill of her underlings has pushed nearly all the demonic invaders out of Avernus.

The Warrior’s General

Zariel is no politician. She lives to fight, and she bases her assessment of those she meets on a combination of their combat skills and their willingness to use those skills. In Zariel’s eyes, zeal and fury are as important in a fight as iron discipline and extensive training.
That outlook has made her something of a political pariah, since she has spurned overtures of alliance from other Lords of the Nine and elected to swell the ranks of her armies through the aggressive recruitment of mortal souls. Her agents offer gifts of martial skill and courage to any who are willing to bargain. Zariel needs souls that yearn to prove their worth on the battlefield.

Lady of Ruin

Zariel rules over the ruin that Avernus has become. Once it was a bustling realm filled with cities, trade outposts, and other features, but recent activity in the Blood War has reduced it to a blasted wasteland. The few structures still standing are citadels constructed by the devils to repel attackers, to be rebuilt each time the front line of the war moves. The devils are in control of Avernus at present, though the fighting goes on (as it always does) in isolated locales throughout the layer.
Adventurers able to avoid the other occupants can find treasure within some of the ruins, though they must venture to the fringes of the active conflict to have any hope of finding places that have not yet been looted.
Many of the active citadels on Avernus loom over the River Styx or surround portals to other planes or to Dis. An amnizu presides over each location, directing the lemures that emerge from the Styx, marshaling forces against invaders, and preventing unauthorized travel.

Keep wasting my time with your pointless words and die, or join my war band and live. Choose swiftly. I have a plane to conquer.

— Zariel addressing emissaries from Dis

Ruler of the 1st Layer of Hell - Avernus

Aligned Organization

Lord's of the Nine

TIAMAT WAITS AND WATCHES

The Queen of Dragons resides in Avernus. Her lairs sits atop a towering mountain, with flights of dragons wheeling through the skies to discourage any demonic incursions. For their part, the demons avoid this place. The hordes of the Abyss have learned the hard way that Tiamat and her court prefer to be left alone. She appears disinterested in becoming involved in the Blood War.
Tiamat’s presence in Avernus has confounded sages for years. As with devils, she is unable to leave the plane of her own will. She must be called forth, but only the mightiest rituals can draw her back into the world. So, if she has been imprisoned here, how and why did that come about?
The most prevalent theory holds that her confinement is related to the end of the long war between the dragons and giants, that she was sequestered here by means of a mighty curse levied by a forgotten god of the giants she slew. The curse brought an end to the war but also drew the curtain on the time of the dragons and giants on the Material Plane, clearing the way for the rise of humans, orcs, dwarves, elves, and other folk. If Tiamat were to return to the material world, that event could trigger, or be a signal of, the resumption of the war between giants and dragons.