The Briar occasionally jokes that bastardry explains her excellence; she's just that much less inbred. Her blood is as blue as anyone's, though, so she's also mocking herself — her father was a member of House Romante, her mother the Duchess Sokar. Given the obviousness of her existence, they elected to recognize her, and she was raised as a Sokar rather than a Romante, but flitted amongst both families regularly.
She never really felt the stain of her birth; she was too busy having fun. Blessed with unspeakable brilliance, this was expressed in everything from mastery of language to a sublime ability to read people (and an insatiable curiosity about nosign into her business). Her greatest prodigy, however, was as a commander.
House Sokar is famous for falling under bad leadership until relatively recently, and a major reason for that is how Briony was firmly excluded from high-level decisionmaking as much as possible, out of jealousy by her legitimate siblings, and her mother's protectiveness of them — god forbid they be eclipsed by her bastard. So, she went elsewhere, fiercely motivated to put herself to use from the start. She trained with (and ultimately led units of, in both the Civil War and the Thirty Years War) the archers and sailors of her House, who cared a lot less about where she came from. She drifted into Romante circles, and as that house was winnowed away, became good friends, and something of an elder sister figure, to Melisande.
During the civil war, she wanted to give Melisande quite a bit of outstanding strategical insights but was kept from doing so by the simple expedience of Sokar making her a Lawkeeper, in an attempt to tie her hands back home. This was a mistake; she took to justice like a fish to water, and rooted out corruption with ferocious competence, first at home and then, after the war, throughout the kingdom, when Melisande elevated her to a nationwide Lawkeeper, a Countess with one of the border fortresses to her name, and to corrupt nobility, an unbelievable pain in the ass. Occasionally she wields sword or bow in the Queen's service; but her most dangerous weapon, by far, is her incisive mind (with second place going to her powerful presence, usually leveraged as intimidation, though she can be pretty charming when she's off the clock).
Briony doesn't have a lot of noble friends — she is feared, and rightly so, because she has a habit of cutting through the gordion knots of their bullshit with style (if not always grace) and, if necessary, with force. She cheerfully associates with people of all origins, and has a certain bias towards the relative honesty and awesomeness of commoners, in part because Sokar's are, indeed, tremendous. Her most notorious rival is Gauvain Tarris; she fought against him in the Civil War in places, before he turned, and is legendary for being the one person he never could beat. They have a stormy, on-again-off-again romance that has spanned decades, and the two of them in the room has a distressing tendency to devolve into a contest of one kind or another.
One of her daughters is his, but she'll never tell. She has three: Helena and the identical twins, Lara and Tara, taught to use their similarity to their advantage rather than as a burden to resent. She refuses to disclose the identity of their fathers, uninterested in having them scorned for common blood, nor their rightful inheritance stolen by noble fathers, as the case may be. She loves all of them fiercely, and has taught them to be as take-no-shit, kick-your-ass, in-your-face as she is. When she's away, and she often is, to the extent that they need be in the care of anyone, they stay with her best friend, who is also her steward (she needs one; she studies stewardship in her uncopious spare time, but it isn't her strength) and possibly the best archer in Galenthia.
Today, Briony is known as The Briar, as in the Briar and the Rose; anyone who starts messing with Melisande has to deal with her thorns, and as the kingdom's top Lawkeeper she is all too happy to look into your schemes and tear them into little bitty bits. Every rose has its thorns, and Melisande's is Briony. Marshal, spy, sheriff, sister; she plays many roles for the Queen, and all of them gladly.
She plays one more role that not even the Queen knows about: as a Knight-Sergeant of the Order of the Vigil. She has steadfastly refused to be promoted further up the ranks due to the necessity of her being constantly on the move — in her own words, "In the trenches is the place for me." But, sooner rather than later in her career as a Lawkeeper, nearly twenty years ago, she got sucked into one supernaturally-tainted mystery after another. She impressed the Order with her tenacity at following leads and her cleverness in ultimate execution, and when she got sufficiently in over her head, they intervened, saved her life, and explained what was actually behind all of the weirdness. She's been one of their agents ever since, and while she's far from the most effective on the front lines, her brain is their secret weapon when it comes to issues of long-term strategy or investigation against an ongoing threat. She's also done two tours of duty as a Knight-Warden; in the periods after each of her pregnancies when it was necessary to stay in one place if she wanted to be in her kids' lives when they were too young to travel. Conveniently (and problematically), there is a Banshee in the Sokar lands, and she has come to know it all too well over the years. She was one of the Vigilants present at the sealing of the banshee who destroyed Jaren's home, and took a scar in that battle that runs, long and thin, from just below her collarbone to her navel. Long since familiar with and fond of the Queen's then-bodyguard and now-Champion, she's delighted that he's joined the secret war.
Among the Order, she is known as Briony Silverbow; half of the arrows in her quiver are always made of the precious metal, though she eschews offers of Lightsilver, pointing out that arrowheads need not withstand rigorous, sustained use. After a decade of service the Knight-Commander essentially forced a Sidhe-Steel dagger upon her, and she often wears it on a chain tucked beneath the neckline of her shirt, easily mistaken for a pendant of some kind.