The Citadel of Darkness is a location that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. It is Dark Mobius's counterpart of the Citadel of Darkness. It serves as the heart and headquarters of Dark Enerjak.
The Citadel of Darkness's early history was most likely largely the same as its Mobius Prime counterpart's. The point of divergence was when Knuckles became corrupted by his chaos powers and decided to conquer Mobius.
Some time after assuming the mantle of Enerjak, Knuckles recreated the Citadel of Darkness. Whenever he held an audience here, his subjects automatically bowed to him. Knuckles, however, simply thought it was funny.
The Silver Saga
While chatting with a constrained Remington in his Citadel of Darkness, Knuckles discovered Silver the Hedgehog's arrival in his Zone. Finding this new arrival interesting and worthy to meet in person, Knuckles cut his meeting with Remington short by extracting his Core.
After Jani-Ca had seized the power Knuckles wielded as Enerjak, Jani-Ca went to the Citadel of Darkness with Knuckles so she could restore every Core Knuckles had taken. Not yet willing to forgive Knuckles or regard him as her father again, she brought him along for insight. With Knuckles guidance, she concentrated on wanting to enter the citadel, and they arrived at a throne room where she hesitantly followed his instruction to sit. Jani-Ca extended her will again and the ceiling vanished, revealing all of Enerjak’s victims.
Surveying the figures, Jani-Ca was surprised to find Dr. Eggman among them as she thought he had been vaporized, and Knuckles explained his experiments to restore Eggman since the Doctor was the first person he stole a Core from. Since Knuckles never tried restoring a Core to someone, she found herself unsure where to begin or even how. Seeing this, Knuckles warned she could not without mastering her powers, and suggested coaching her by example if she shared some power with him, but a look from her silenced him. Jani-Ca then heard a dark voice whispering malicious ideas in her mind, but ignored it as those thoughts led to the misery she grew up in and refused to perpetuate it, though she knew she would not be able to resist forever.
As Jani-Ca considered who to try restoring first, Knuckles suggested Julie-Su only to add that Jani-Ca would not start with her because she would not want to risk a mistake and lose her mother. Seething, she reluctantly agreed, but resolved not to sacrifice anyone else to his machinations when he proposed using a villain like Eggman who would not be missed. Eventually deciding to use Remington as a test subject after realizing that is what he would have wanted, she presented a Core to his body, praying he would wake up.