Sigrun War-Blade is a second-generation Nord born in Cyrodiil who was forced to flee the main Imperial province because of her willingness to defend her father, Tolgruf War-Blade, from a Thalmor lieutenant who'd stopped by her family's smithy for some extra fletchings - only to end up threatening the aging smith when the price didn't suit him. She killed the fop and disposed of the body, and she'd gladly do it again.
Unfortunately, her father and the Imperial Watch didn't agree. So, with no other choice but to flee, she managed the perilous trek from the Imperial City to the Jerall Mountains past Bruma. She might be built like an oak, but having to keep silent and still allowed her to develop a bit of a forceful aptitude at stealth; even when wearing a full suit of plate armour.
Still, that wasn't enough. One fine morning, as she crossed the border into Skyrim, she was picked up by some of General Tullius' men, along with some of the retreating Stormcloaks. She doesn't know it, but her ancestor was the Hero of Kvatch. Thorsen War-Blade, Martin Septim's last protector, was blessed by Talos, late in life. For his accomplishments, his misdeeds prior to his adventures as the Hero of Kvatch would be wiped from the annals, and he would be named Dragonborn. Talos, as he appeared in the dream, stated that the Emperor's amulet still wouldn't fit him. The Nine would know him as Dragonborn, but the mortals would remain in ignorance - for their own good.
Thorsen's last contribution to the safety of Tamriel had already left his loins years ago, Talos said. It wouldn't be his son, or his son's son who'd seal the War-Blades' ties with the throne.
Sigrun knew the story, but she'd always thought it was just another one of Tolgruf's drunken ramblings. She knew about her ancestor's heroism, but Thorsen had allegedly returned to Whiterun, her family's ancestral roots, to die.
After killing Mirmulnir, however, all of the old stories came rushing back. It was all true, then, and she didn't know what to make of it. What didn't help was that her first uttered Thu'um was a complete disaster that actually got her jailtime...
As for the civil war; she was born and raised in the Imperial City and sees the Thalmor as a creeping vine feasting on the stronger oak. She honestly wasn't surprised when she understood that Ulfric Stormcloak was a sleeper agent for the High Elves. True Nords are steadfast in the support of their friends and allies, regardless of their race, colour or allegiance. True Nords aren't spiteful blowhards who recite tales of glory and expect some other champion's feats to brush off on them. She's met plenty of Imperials she didn't like, but the Stormcloaks make her sick to her stomach.
That's pretty much my girl to a tee.