Syl

Syl is a character from the Elder Scrolls: Oblivion video-game and a leading figure in the Shiver Isles, specifically the region known as Dementia - which is the portion of the Shivering Isles inhabited by dangerous psychopaths, many of which share Syl's nature of paranoia: indeed as well as her official role as Duchess of Dementia she has earned herself the title of Lady of Paranoia due to her extreme level of such sickness.

History
Syl is the Duchess of Dementia and has long been troubled by visions of her own demise by innumerable enemies (both real and imagined) - she employs the player hero to aid in exposing the conspiracy against herself, appointing them as her Inquisitor and warning them if no results were made she'd see the player hero as responsible and punish them accordingly - to aid them in their quest she provided the service of her torturer, Herdir.

Together the hero and Herdir uncover the conspiracy against Syl and it turns out a citizen by the name of Muurine had been planning Syl's death due to her affairs with the Duke of Mania - Muurine is thus arrested and confined in a cage by Herdir.

Syl arrives personally to perform an execution, pressing a button which activates an execution-machine near the cage, electrocuting Muurine to death - she then returns to her "duties" as Duchess but her paranoia remains.

During the Ritual of Accession she is either killed by the player hero to obtain her heart or becomes enraged when the player kills Thadon, thus results in her joining with the Forces of Order, where she must be fought and slain by the player hero.

Personality
Syl is a proud and strict ruler guided by a deep and uncontrollable paranoia, she sees potential ruin and treachery in everyone around her - this motivates her to extreme acts such as the torture and imprisonment of her own people and shows no qualms about killing anyone that may pose a threat (whether real or imagined).

Syl's paranoia is half due to her madness and half due to her affair with Thadon, the Duke of Mania, whom her people despise as an enemy - ultimately her paranoia was proven to be somewhat justified as a conspiracy had indeed been made against her but even after the death of the traitor her paranoia remains, showing that she is still a deeply troubled and dangerous woman.

Abilities
Syl is a supreme monarch (or at the very least high-ranking noble) and as such holds power of an entire Court, she has personal guards and agents as well as authority to enlist anyone she may desire to aid her task - this makes her a formidable opponent and a fearsome leader, especially when combined with her unpredictable nature.