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Siora was born in Rihad just after the Great War. Her mother was a former priestess of Dibella and her father was a high ranking soldier in the Imperial Army before Hammerfell's ejection. Her mother wanted her to be more ladylike but she took more interest in her father's martial skills. He taught her what he could when she was small. When she was around age ten, her father was killed in a duel with a nobleman in Rihad, who challenged him after her father defended the Empire's decision, citing its precarious position.
Siora, watching from the crowd, saw what no one else did, that the nobleman cheated. She tried to tell people, but no one would listen except her father's life-long friend and mentor. She was grief-stricken and vowed revenge, and her father's friend promised to help train her to be the warrior her father was.
Over the years, she surpassed her father in every way, turning out to be quite the prodigy. At twenty, both she and her mentor felt with both her skills and the political climate, it was time for her to take her revenge. She challenged the nobleman to a duel. He could not refuse because of an already weak political position, and being seen as even weaker would completely undermine him amongst the nobility. Once again, he attempted to cheat, but she was ready for it and slew him.
Unfortunately, though he was not well liked by the nobility, he was fairly popular amongst commoners. She and her mother became pariahs. Realizing the price of her revenge was too high on her aging mother, she made the decision to leave. She left her mother a kindly worded letter, saying that she should disavow Siora's decision to kill the nobleman, and to say that she sent her daughter away out of shame.
Siora crossed the river to Anvil and spent several years as an adventurer and mercenary in Cyrodiil. She gathered a band of three friends that gained great fame. Unfortunately after a disastrous quest where her companions were slain, Siora felt it was time to move on. She headed north to Skyrim, by way of Pale Pass, and in her meloncholy, was caught unawares in an Imperial ambush, where she was captured and put on a wagon to Helgen...
Siora's actions are governed by a strong sense of right and wrong. Being a prodigy swordswoman, they are further tempered by the need to find a good fight, as she has yet to find anyone who can match her and earn her respect. She respects loyalty and camaraderie, and despises lies and treachery. She has no ill-will towards the Empire itself, understanding their precarious position thanks to her father. She believes the Stormcloaks to be misguided idiots who will, if successful, divide and weaken the Empire and cause the Dominion to renew their invasion, something that a completely divided Tamriel would be unable to resist.