Precia Testarossa, also transliterated as Presia, is the first main villain of the Magical Girl Lyrical Nanoha series; however, she does not appear in Triangle Heart. A mage and the main resident of the Garden of Time, Precia sends her daughter Fate Testarossa out to Earth to collect a set of Lost Logia (ancient and powerful magical artifacts) known as the Jewel Seeds, while evading the Time-Space Administration Bureau. While a researcher of familiars, she does not have one of her own during Magical Girl Lyrical Nanoha, and her weapon is unnamed.
Precia first appears in episode 7, having previously been mentioned as the reason that Fate is gathering Jewel Seeds. She is abusive and cruel, torturing Fate simply for not getting enough Jewel Seeds and not disposing of potential hindrance Nanoha. Though Arf hates Precia and tells Fate that she is not worth it, Fate asserts that she remembers a time when Precia was kind and stable, and thinks that she will be cured of her insanity if she gets the Jewel Seeds.
Precia lives in a gloomy hideout in the Garden of Time with Fate and Arf, although the latter two generally "live" in their apartment in Uminari City more than the hideout itself. Precia spends the entirety of the series in the Garden of Time, and always transformed, except in flashbacks. She used to be a scientist involved in many areas of research, including the creation of familiars, but had another secret, forbidden project.
[Spoiler] Late in the series, Arf finally strikes out at Precia, and is thrown out as "useless". Precia supervises Fate's winner-takes-all fight with Nanoha, and when Fate loses, sends a storm to attack Fate and steal her Jewel Seeds before she can give them away. The Time-Space Administration Bureau, having joined up with Nanoha and labeled Precia as a dangerous criminal, traces her to the Garden of Time and attempts to capture her. Precia defeats their first group of soldiers and, realizing that Fate is among those observing her in the Arthra, reveals that Fate is a clone of her biological daughter Alicia. Precia went insane when Alicia died and concentrated herself on her secret project, which researched both cloning and the forbidden art of resurrection: Project Fate, from which Fate Testarossa takes her name. She also reveals that Fate was a temporary replacement, a tool to get the Jewel Seeds so that Precia could go to the ancient capital of the magical worlds, Al Hazard, and retrieve the lost technology that could finish her work.
Precia activates the nine Jewel Seeds in her possession and wishes to go to Al Hazard. This action causes a massive dimensional disturbance, and the Garden of Time begins to fall apart. When Fate joins up with Nanoha and the TSAB forces, she attempts to save Precia, but the crazed mage refuses, laughing in her face and choosing to die with the preserved body of Alicia rather than face a several-hundred-year sentence for her crimes. In the end, she falls without a struggle into a dimensional void. [/Spoiler]
(Source: Wikipedia)
[Spoiler] In the movie it was revealed that Precia was always busy with work and never had time for her daughter. She had promised that the two of them would spend time together before Alicia started school. But durring an experiment Alicia died driving her mother mad with guilt. As she falls to her death she remembers Alicia saying that she always wanted a little sister and thinks to herself "I never notice things until it's too late." [/Spoiler]
