Archdevils

The Archdevils, also known as the Ascended Devils, were the eight most powerful devils in the infernal plane. Each was given their power by Asmodeus and a layer of the Nine Hells to rule over. These positions fluctuated with time, as Asmodeus gained and lost faith in one devil or another, and as backstabbing occurred within the ranks. It was not uncommon for an Archdevil to be betrayed by one of their servants and slain, at which point Asmodeus would promote the betrayer to Archdevil for their bloodthirsty determination.

The Archdevils could reach near a Lesser-God level of power, through this varied and fluctuated depending on their standing with Asmodeus. However this all changed when majority of the Archdevils and Asmodeus were slain by a mortal whose name was forgotten with time but is referred to as the Original Sinner. This shook up the infernal plane as majority of the archdevils were slain and in their place new archdevils were put in place. With Asmodeus out of the way and many of the archdevils dead or very few fled to the mortal plane along with some other devils it made it easy for the Outsiders to tear apart the infernal plane and remove it from existence. Now all the devils, demons, and few archdevils along with some of the demon princes live amongst the mortal plane causing chaos amongst mortals. Now the Archdevils that remained are slowly becoming dread lords or Star Signers and have around the same power level as them, which can compare to higher gods or in some cases the power of a sealed god. This sparked many demonic cults and dark cathedrals to be built within in Dephiron as a place of "worship" and "sacrifice" for these archdevils and other devils to "defend" the rest of Dephiron from being destroyed however in actuality this is a means for Archdevils and devils to become stronger slowly turning the mortal world into the infernal plane.

Former Hierarchy
The Archdevils were once arranged by power and prestige by the layer they presided over. However, their power and important were not necessarily absolute, as many occupied pivotal roles necessary to the status quo of reality (Zariel's position in the outermost layer of Avernus did not reflect her immense importance as the High Commander of the Nine Hells.) The Hierarchy fell when the Original Sinner and his order entered into the nine hells slaughtering those that stand in the way.

Avernus

 * Zariel: Archduchess of the First Layer, and the Higher General of the Nine Hells. A fallen angel who was granted her position by Asmodeus under the promise she could one day lead the armies of the Nine Hells against the gods, so that she could claim her revenge.
 * Bel: A general under the command of Zariel and a former archduke himself.

Dis

 * Dispater: Archduke of the Second Layer. A very paranoid fiend who preferred to act behind the scenes and through various proxies.
 * Lilis: A loyal consort of Dispater and his primary advisor
 * Arioch A vassal of Dispater who meted out vengeance on those who dared to defy his master.

Minauros

 * Mammon: The Archduke of the Third Layer. The embodiment of greed amongst the Archdevils, He was very uncontrollable always after something to add to his collection. He often was the reason that some Archdevils lost their position.
 * Bael: A powerful enforcer that serves Mammon

Phlegethos

 * Fierna: Archduchess of Phlegethos. A fiery and beautiful fiend who loves to deduce and corrupt mortals, especially paladins and clerics of good aligned gods.
 * Belial: The previous Archduke of Phlegethos and Fierna's father. He voluntarily gave up rule for his daughter on the condition that he becomes her primary advisor, which granted him a massive amount of power and influence.

Stygia

 * Levistus: Archduke of the Fifth Layer, imprisoned in an iceberg for all of eternity as punishment for his past crimes against Asmodeus. Strange enough, Asmodeus allowed him to retain his position as Archduke. He acts by telepathically communicating to his underlings mainly Agares.
 * Agares: A Commander of Stygia. He was once a duke under Geryon's reign but found a new position as a commander under Levistus due to his combat status. Was the most powerful among the devils in that Layer and was favored by Levistus.
 * Geryon: He was the previous archduke of Stygia. Geryon was a savage archdevil who seeks to reclaim his former position but was unable to due Levistus' imprisonment.

Malbolge

 * Glasya: The Archduchess of the Sixth Layer and Daughter of Asmodeus and sister of Xallen. She is in charge of overseeing the Erinyes and their activities.

Maladomini

 * Baalzebul: Archduke of the Seventh Layer, also known as "The Lord of the Flies." He was a master strategist and had a near perfect plan to over throw Asmodeus, but if it wasn't for the demons the ruined his plan and the one bad move he made he would have over thrown Asmodeus.
 * Yase: A Duke and General that used to serve Glasya.
 * Eshudel: A Duchess and General that used to serve Xallen.

Cania

 * Xallen: Archduke of the Eighth Layer. Deposed the previous Archduke Mephistopheles and his daughter by becoming a spy for his Father and supposedly "aiding" Mephistopheles and his daughter eventually betraying him in a plot to kill and replace Asmodeus.
 * Drannoron: A fiend who was once a great warrior in life, he was Mephistopheles' daughter's husband who was turned into a fiend as punishment for attempting to bring down Asmodeus along with Mephistopheles. He served Xallen as a High General of Cania.
 * Zelzosa: Once an adventurer who got caught up in the scheme, She fell in love with Xallen and was granted a new life as the High General of Cania however she is never became the wife of Xallen.

Avernus

 * Zulthir: Archduchess of the First Layer and the one who killed Zariel and Bel. Much like Zariel she also seeks vengeance on the gods however she sides with the Outsiders instead of Asmodeus.
 * Altirth: A general under the command of Zulthir.

Dis

 * Vrakro: Archduke of the Second Layer and the one who killed Dispater and Arioch. He used Arioch's loyalty to Dispater to his advantage by using the Outsider's power to pit one against the other and killing the one that remained.
 * Lilis: No longer a consort and primary advisor of Dispater but still remains loyal to him. She is presumably one of the fiends that roams the mortal plane looking for a way to bring Dispater back.

Minauros

 * Mammon: The Archduke of the Third Layer. He allowed the Original Sinner and his group aid in their plans in exchange for allowing him to remain as the Archfiend of Minauros along with keeping Bael as his enforcer. He supposedly ascended by some strange entity that was an Outsider.
 * Bael: A powerful enforcer that serves Mammon. He also roams the mortal plane along with Mammon abusing people's greed.

Phlegethos

 * Fierna: Archduchess of Phlegethos. No longer contained by the infernal plane now roams the mortal plane seducing paladins and clerics that are good aligned.
 * Imorm: The new advisor for Fierna after making a deal with Belial making him something more which granted him more power and influence than his previous position.

Stygia

 * Geryon: Archduke of the Fifth Layer, worked with the Original Sinner and his group to get his position back, however it wasn't for long as the infernal plane was destroyed by the Original Sinner. It is unknown what happened to Geryon, some speculate that he is attempting to get vengeance on the Original Sinner.
 * Iahoz: The new commander of Stygia who was close with the Original Sinner. He slaughtered Agares becoming a commander under Geryon but mainly as a spy.

Malbolge

 * Glasya: The former Archduchess of the Sixth Layer and Daughter to Asmodeus and sister of Xallen. Was the first to leave the infernal plane taking the Erinyes' with her. She stepped down from the position as she knew she would be killed. Not much is known about what happened to her.

Maladomini

 * Brodran: Archduke of the Seventh Layer, Outsmarted Baalzebul using him as a sacrificial pawn promising to help him overthrow Asmodeus as long as he helped with their goal. Baalzebul was betrayed and slaughtered after he served his purpose.
 * Eshudel: Slaughtered by Yase. The two were pitted against each other as entertainment the winner was supposed to live and ascend to a better position however the two killed each other.
 * Yase: Slaughtered by Eshudel. The two were pitted against each other as entertainment the winner was supposed to live and ascend to a better position however the two killed each other.

Cania

 * Xallen: Archduke of the EIghth Layer and Son of Asmodeus. Much like Glasya not much is known about what happened to Xallen during the invasion nor if he was slain or lives.
 * Drannoron: A fiend who was the husband of Mephistopheles' daughter and was a powerful warrior in his life. He was freed by the Original Sinner and swore to work under the Original Sinner ever since.
 * Zelzosa: Status is unknown. She is presumed alive as she was not in the infernal plane when it was invaded.