Asmodeus

Asmodeus is the Archduke of Nessus, Ruler of Baator, and Lord of the Nine. Thousands of years ago, Asmodeus was a powerful angel in the service of the ancient dead god He Who Was. In his early service, he fought against the demons of the abyss on the behalf of the gods, attempting to destroy them and win the war against Tharizdun. After the War of Many Suns, he was charged with guarding the Mad God's prison. However, his extensive time in the Abyss corrupted him. Then, during his time guarding this cage, the ancient Obyrith Lord Pazuzu appeared to him and whispered dark temptations and secrets into his ear, furthering the corruption that had been seeded within him. During this time, the angels who had fought within the Abyss for millennia had become devils. The gods, rejecting the evil form of these fiends, left them stationed with Baathion, the original realm created by He Who Was.
With the corruption that Pazuzu bred within Asmodeus, he became darker and more powerful, as well as beginning to plan a rebellion against his master, He Who Was. Eventually, he abandoned his post at Tharizdun's prison, plunging deep within the Abyss to its very deepest layer, to its heart. There, he tore a piece from the Shard of Evil from which the Abyss itself grows to this day. With this shard, he secretly crafted the infamous Ruby Rod of Asmodeus. He then led some of his fellow angels whom he had managed to sway to his cause against their master, killing him in a surprise attack.
With his final breaths, he cursed Asmodeus and his fellow revolutionaries, casting them down from the heavens into Baathion, killing all of them save for Asmodeus and sealing the devils and Asmodeus within Baathion and turning it into a scorched wasteland. The fall of these angels was so great that it shattered Baathion into nine layers, now known as the nine layers of hell. From then on, Baathion became known as Baator and these dark angels became known as the devils, cursed into hideous and evil forms for eternity. As such, Asmodeus is the oldest of all of the fiends, with age rivaled only by Dispater and Mephistopheles. Within it, Asmodeus, despite being wounded from his fall from grace, was the most powerful of them and came to rule over them, overthrowing and killing the original ruler of the plane, Zargon, who had come to Baathion from the Far Realms, feeding off of the evil of the dark angels.
Being the most powerful being in the plane, Asmodeus quickly established himself as the supreme overlord of the Nine Hells. He would then go on to create the Pact Primeval, successfully debate against the angels and gods in two separate trials, and even gain ascend to divinity.

Divine Domains

Sin, order, contracts, knowledge, trickery

Divine Symbols & Sigils

Three black triangles forming a downwards-facing isosceles triangle on a red field.

Divine Classification

Archdevil, God

Alignment

Lawful Evil

Honorary & Occupational Titles

Lord of the Ninth, Master of the Hells, the Prince of Evil, the Archfiend, the Lord of Nessus, the Lord of Lies

Quotes & Catchphrases

"Read the fine print."