Darkness.
Darkness enveloped the spirits' every thought, every action, every movement. To some spirits, especially the more sadistic ones, darkness was a welcome reprieve from the blinding light that had been recently cast upon Alagaësia. In fact, some spirits even chose to seclude themselves from the mundane activities that now occurred on a daily basis. However, when darkness was their only sensation for as long as they could remember, not one of the spirits basked in its glory. These were Bristene spirits, the most violent of their species, and, by far, the most dangerous.
There had once been a time that they had been free. Oh, how joyous life had been then, when they wreaked havoc in all corners of Alagaësia! No dwarf, human, elf, Urgal, or even Ra'zac could have stood in their way; and, indeed, rarely any of them dared to cross the spirits' path. The few that attempted to cast away the spirits, needless to say, suffered greatly from their ignorance. And all was well, all was happy.
Then the dragons came. Like a rancher to his cattle, the dragons slaughtered many of the spirits, driving many more underground into hiding. Their extermination was only exacerbated after the dragons adopted humans and elves as Dragon Riders. Their combined strength nearly wiped out all of the spirits, save for a few who vowed not to disturb the peace of the land.
However, a few spirits resisted. These were the most powerful of them all, unmatched in manipulation and power. They fended off the Riders for many generations, creating a longstanding impasse between the two groups. The spirits tended to occupy the areas in and around what is now the Hadarac Desert, while the Riders extended their control all across Alagaësia: from the massive peaks of the Beor Mountains to the regal city of Doru Araeba. And for a time, this stalemate lasted, neither side willing to make a move for fear of retaliation.
Finally, a spirit, brash in its youth, decided to infect an elven Rider by the name of Tithaën, who had accidentally ventured too far into the Hadarac Desert while en route to Ellesméra, the elven capital deep in the forests of Du Weldenvarden. After breaking his mind, the spirit took control of Tithaën's body and proceeded to slay his own dragon, Carnaea. Eventually, realizing what he had done, Tithaën committed suicide as his penance for allowing himself to be controlled so easily.
The dragon's wrath at this course of events can only be equated to the Banishing of the Names, and even that paled in comparison to the retribution they unleashed upon the Bristene spirits. Compiling their power into one spell, the dragons cursed the spirits to an everlasting darkness, impossible to escape from. Well, nearly impossible. The dragons could not curse anything for all of eternity, because eternity had no end; thus, they would only kill themselves if they did so. The dragons thus decided to tie their magic to what they considered to be the most improbable event: the spirits could only be free when the Riders abandoned Alagaësia. Satisfied with their work, the Riders proceeded to extend their control across the Hadarac Desert, and the land was at peace once more.
Or so the story is told. The tale of the Bristene spirits was a common story, meant to portray the Riders as a benevolent force dedicated to preserving peace. However, the Riders had an ulterior motive for banishing the spirits. While the spirits resided in the Hadarac Desert, they had been searching for a way to eliminate the Riders, and all non-spiritual beings, in one fell swoop. The Riders learned of these plans and quickly blamed the spirits for some minor event in order to justify their actions. In actuality, Tithaën and Carnaea were never killed due to a spirit, but instead had committed suicide to protest the ineffectiveness and corruption of the Riders. After banishing the Bristene spirits, the Riders disposed of all evidence indicating the spirits' plans. In fact, they themselves did not know much about the plan, only finding one phrase engraved in the stones of Du Cimiter (or, as the Riders renamed it afterwards, Du Fells Nángoröth): The End of Days.
And since that fateful event, the Bristene spirits had been locked in a pit of eternal darkness, in a place that simultaneously existed and failed to exist. Most of the spirits had consigned themselves to solitude, having long given up hope of their release. But a few of these spirits held out hope, hope that one day the Riders would abandon Alagaësia so that they could be free once more. After all, they now had a purpose that they did not have before. Before they were banished, they wandered freely and killed whomever they chose, and while many appreciated this freedom, they had no goal, no purpose.
However, in their arrogance, the dragons had left out one crucial part of their spell: they never forbade the spirits from using magic during their imprisonment. Unlike other spirits, Bristene spirits tapped into magic to live. While the dragons deemed it useless to forbid their use of magic (as none of their magic could affect the real world), the spirits had spent every last ounce of their energy over the past centuries trying to accomplish what they had failed to do before: bring about the End of Days.
Chief among the proponents for this plan was Argëtling, the "leader" of the group, if such a term must be assigned. He had spent millennia plotting the destruction of mankind, and he had nearly succeeded. The spirits, after eons of arduous work, had finally created what they had never before done. They had created something that would bring about the End of Days.
But there were two things needed before they could release their secret weapon: they needed to escape their torment, and they needed to prepare the world for the End of Days. So, for years, they sat in anticipation, waiting for when a Rider would finally abandon Alagaësia. They expected to wait for another few centuries before such an event would occur. Unbeknownst to them, the Dragon Rider Eragon Shadeslayer and his dragon Saphira.
In the interim, Argëtling was focusing on his own life, before the banishing. His spirit was the most terrifying and awe-inspiring of them all. No dragon or Rider was his equal, even when they were combined. But his anger festered for millennia after he was banished. He was not bested by a superb power or one that could hope to compete with his mental prowess. No! Instead, he was defeated by an underhanded magic trick by which he had no defense against. He had vowed, long ago, that if he was ever given the opportunity to fight another Dragon Rider, he would do everything that the Riders claimed that he did. He would break their minds, force them to kill their own dragons, and then relish as he tortured them both physically and mentally.
But no such opportunity came, and Argëtling, the most determined of the group, was even beginning to question if they would ever be released.
Then finally, one fateful day, light burst through the Bristene spirits' prison. To many of them, it was such a foreign experience that they did not immediately try to leave their imprisonment. However, Argëtling had toiled for too long in the pit, and left for the outside world with no hesitation. Finally! No longer would they be confined to the darkness of their prison, but now allowed to sow chaos throughout the lands. What, he wondered, would life be like now? More importantly, how long would it take to bring about the End of Days? After all, that was his primary goal. But he still relished in the idea of him destroying the current generation of Dragon Riders.
And although he was a disembodied spirit with no physical form, one could swear he was smiling.