Formora was a female elf, bonded to a brown dragoness, who joined the Dragon Riders at a young age. She and her twin brother Kialandí were trained in the ways of the Riders and eventually joined Galbatorix on his quest to conquer Alagaësia. As such, she became one of the infamous Forsworn.
Not much is known about Formora's early history, but it is known that she and her twin brother Kialandí were chosen to become Dragon Riders and she became bonded to a brown dragoness and trained in the way of the Dragon Riders by an unknown teacher.
In the time that Galbatorix was gaining power and followers, two senior members of the Order decided (partly at the urging of Formora and Kialandí, who had also join the Forsworn) to find out what they could about the whole situation for themselves. These were Oromis and his dragon partner, Glaedr.
Oromis and Glaedr took Formora and Kialandí, who had recently returned from patrolling the Spine Mountain Range, with them on their venture and after a short time of flying, the treachery of the latter two was revealed. The senior Rider and dragon were caught in a spell that almost stopped their movement. While in this hex, Formora and Kialandí were able to cast wards around the pair, this time stopping their movement altogether. As soon as the wards were placed, however, Oromis and Glaedr lashed out with their minds.
A vicious mind-battle ensued, one that lasted for several hours. Oromis and Glaedr versus Formora, Kialandí, and the latter two's dragons, as well as the Eldunarí of the dragon Agaravel, whose body and Rider were killed by Kialandí and Formora. Glaedr, in a later recount of the incident, recalled the battle as distinctly unpleasant.
When it became apparent that the battle could not continue for much longer, Oromis cast a complex and extremely difficult spell that managed to free himself and Glaedr from their bonds. Just as Oromis finished his spell, Formora cast a spell that Galbatorix had learned from the shade Durza to bypass Oromis' wards and permanently prevent him from using magic. Formora's spell only worked in part because of Oromis' spell and he had the first of many seizures that would consequently plague him throughout the rest of his life. Glaedr fended off Kialandí, Formora, as well as their dragons in order to protect Oromis during his seizure and managed to separate himself and Oromis from them. During the struggle, Kialandí was impaled and badly wounded on the spikes of his own dragon and was therefore incapacitated as Oromis and Glaedr made their escape. Formora and Her Dragon, however, were able to follow.
In her bloodlust, Formora attempted to kill a weakened Oromis with a slice of her sword, but Glaedr twisted to avoid the blow and as a result, the dragon's left foreleg was severed. It was stated later by Glaedr that Formora's victory worked against her, for without the weight of his leg, he was able to escape. Eragon also felt an emotion from Glaedr that was described as a cold, pinching sensation, the one Glaedr felt when his leg was cut off, as if Formora's blade was made of ice, not brightsteel.
Soon after their failure with Oromis and Glaedr, Formora and a newly-healed Kialandí flew to the plains of Du Völlar Eldrvarya, where she fought in the First Battle of the Burning Plains, fighting against the Dragon Riders during which the flames the dragons (including Formora's brown dragoness) of both sides used to attack their foes permanently scarred the landscape. These flames also lit the vast deposits of peat in the area, and the fire apparently "burrowed" underground. Consequently, there are frequent bursts of flame coming out of the ground. The outcome of this battle is unknown.
Formora was also present in the Forsworn's attack on a almost unguarded Ilirea (most of the riders had gone to defend Vroengard). Despite only being a force made out of only fourteen Riders (twenty-eight considering the Forsworn's dragons and Shruiken) against a army of humans, elves, dwarves and Dragons, Galbatorix and Forsworn held their ground, though almost immediately after the battle began, it became clear Kialandí was being doubly attacked within his mind and Formora and her dragon were struggling in a wizard duel of minds against their opponents. Though the outcome of the duel is unknown, the fact that Formora survived the battle to fight concludes that she may have prevailed over her attacker, possibly with the assistance of another Forsworn member or her captured Eldunarí. Though it is unknown, Formora may have assisted her brother, Kialandí fought the Dragon Rider Arva, possibly fighting Arva's sister Naudra while Kialandí fought Arva. During the battle, Formora also fought not just many elves but also many of the finest warriors of a unnamed dwarf clan. Despite the best efforts of the combined forces of the riders, dwarves and elves, the Forsworn eventually ended victories, due to the large amount of Eldunarí they had seized from dead riders, their dragons and the Eldunarí the dead riders also held. Finally, having gained enough Eldunarí to face of against that full for of the riders, Formora, Galbatorix and the rest of the forsworn flew on island of Vroengard, where with the other Forsworn, they laid siege to the Riders at Doru Araeba and destroyed them. During the battle, one of Formora's enemies, an elven rider by the name of Thuviel, who had lost his dragon to the hands of a member of the Forsworn (possibly Formora) only a month prior to the fight, cast a powerful spell in a desperate bid to kill the Forsworn. Half driven to insanity, he remained loyal to the Riders to the end and sought release though he was desperately needed for the fight. By converting his body into raw energy, he caused a release of energy which destroyed himself in a powerful explosion akin to an antimatter detonation. What Thuviel, the Forsworn or the Riders were unaware of was that this was part of a plan to keep a portion of Eldunarí and all the dragon eggs safe from the Forsworn by hiding 135 Eldunarí and 243 dragon eggs, 26 of which had been set aside for the Dragon Riders, in in the Vault of Souls along with the Eldunarí of Vrael's dragon, Umaroth himself, in a subterranean area beneath the roots of Mount Erolas, deep enough to evade magical detection and the memory was magically removed from the minds of all who knew, including the mothers of every egg, Vrael and Thuviel using magic similar to that the Dragons had used in the Banishing of the Names. Galbatorix and most of the Forsworn, including Formora, had some warning and survived by shielding themselves with magic but one of Formora's comrades, a elf by the name of Glaerun and his dragon were consumed in the explosion and were killed. Of the Riders, many were not as fortunate and thus perished, leading the the Forsworn's victory. The explosion also, much to Formora, Galbatorix and the Forsworn's rage, destroyed the hatchery and incubating chamber, which had in fact been emptied of its contests, the eggs being placed in the Vault of Souls. She presumably participated in the elves and remaining dragon riders final attempt to defeat Galbatorix and the traitors with him and may have fought against Blödhgarm or one of his eleven allies, who were known to have survived a duel with at least three of the Forsworn.
Some time after the Fall of the Riders, Formora died under unknown circumstances. It is possible, even likely, that she was driven insane as her Dragon Partner descended into primitiveness. It is also possible she was killed by Brom, or in an attack from the Varden, the latter would have been organised by Brom. A third possibility is that Formora did go mad with grief and had had her death caused or arranged by Brom.
- Unnamed Sword: Formora's Rider Sword. This brightsteel sword was created by Rhunön during Formora's time as a dragon rider and Formora used the sword throughout her life as a Dragon Rider, member of the Forsworn and later life. As Dragon Rider's swords were the colour of their dragons scales, the sword would have been brown in colour. Though it is unknown, Formora's Sword was very likely buried under a unknown battlefield, buried with its wielder or resided in Galbatorix's vast collection of rider's swords.
Since Formora has not made a physical appearance in the books, the extent of her powers cannot be certain. It is likely that she was very skilled at swordplay, mental powers and magic, since she was a Dragon Rider and slew many others of the order, along with quite a few Dragons, Elves and Dwarves, meaning she must have been extremely skilled at fighting, both physically and mentally. She also learned dark magic from Galbatorix and possibly drew power from some Eldunarí she captured during the fall of the riders. Paolini stated that Galbatorix eventually gathered most if not all of the Forsworn's Eldunarí for himself, so Formora power probably lessened since the Riders' Fall.
- She and her brown dragoness are currently the only named female members of the forsworn, although there would have been other female rider and dragon members of the thirteen
- She, her brother Kialandí and Galbatorix are the only members of the forsworn to have siblings.
- She and Kialandí are currently the only one of the Forsworn to be twins.
- Since Galbatorix was unable to find Ellesméra, Formora likely could not have been raised in the elves main cities, or she would have been able to help Galbatorix find it, meaning she would have more likely have been born either in one of the outer areas of the elven forest, or have had been born somewhere else entirely.
- In the Inheritance Almanac, Formora is incorrectly spelled "Formosa".