Marie-Thérèse was born in Nova Scotia to an unsuspecting woman whose husband's name just happened to be Brasseaux. The eldest of seven children, the reality of her husband's family didn't hit her mother until she reached maturity and was taken to be married by a cousin. Impregnated by the age of thirteen, she became a breeding factory, as most women of the family do, spawning more Brasseaux to fight the Sabbat's war for North America. This might have bothered the young girl if her father had not whispered in her ear how important the things she was doing were as he himself added his effort to the breeding program.
This particular girl, however, grew into a formidable woman, driven by the unwavering conviction that this was the way things were supposed to be and that their efforts made a difference in the war and in the progression of humanity towards a brighter future, represented by her and her kin. Her dedication caught the eye of the Tzimisce and when illness and old age threatened to take her life, they chose instead to grant her immortality, so that she may further aid the struggle. Put in charge of the family's breeding program, she proved to be a natural, making sure that any lost sheep were gathered up and that every member of the family lived up to their responsibility.
When her home fell into British hands and her people uprooted, rather than scatter to the four winds or flee to Sabbat controlled cities, she insisted on keeping the family together and finding a place where they might continue to live the way that had for a century in peace. Finding two other like-minded kindred, they gathered all who they could convince and followed the Mississippi River down to the Louisiana colony and settled in the southern swamps, where game and isolation were plentiful. They settled and built the plantation and she set about her work again, leaving Jean-Michel to look after the other affairs, as usual.
Since then, she has led her family through plagues, wars, and conflicts with the Lasombra. While she doesn't really understand the need for the last, she defers to Jean-Michel's judgement as Archbishop. In order to maintain her control over the family, she has chosen one female to act as her mouthpiece, to do her bidding during the daylight hours and enforce her edicts on the others. Unfortunately, she is a little too liberal with the use of Dominate and often these proxies are reduced to mental incapacity after a few decades and have to be replaced. Currently, she is using Émeline and the woman has already had her personality subjugated to the matriarch and her will broken.
During the past century, she has been encouraging interbreeding with the Prejeans in the hope that both lines will benefit from the mixing. She is somewhat concerned about the loss of effectiveness as each side becomes more inbred and decadent and hopes that this might stem the tide. She is loathe to bring in new, inferior blood, just to fortify the stock, but has been willing to allow marriages to lost lines of the family or anyone with even a trace of family blood.
Beneath her autocratic visage, Marie-Thérèse is a fanatic. Her utter devotion to the Sabbat, her family, and the principles of her Path have never wavered in the three hundred years of her existence. Rather than latching onto these things out of the usual elder desperation for context, she is perfectly sincere in a very frightening manner.
Face to face, she is an intimidating persona. While she looks to be merely a comely old woman, the fire of conviction burning in her eyes and her uncompromising manner liken her more to the mad tyrants of ages past. She brooks no disobediance and has been known to set her beloved dogs, Gui and Gil, on even the most powerful and well-liked members of the family when they cross her. She is impossible to sway and most of the family has learned, instead, to bargain with her or merely keep her in the dark about things she would disapprove of. She has a knack, however, for finding things out, and so most of these petty schemes eventually come to light, usually when Gil and Gui come to nail the offending party to the kennel wall.
Marie-Thérèse's usual resolve and conviction only falters when faced with Jean-Michel. She respects him as the leader of the household and the warmaster of the pack and it is only to him that she will defer. This has led to him being thought of as the last recourse when a party disagrees with the matriarch's judgement. She is also fond of the other two elders, though certainly not so much that she'd waver on her edicts for them.
She is, of course, utterly devoted to her family, though she likes some members more than others. She is aware of Gerard's deceptions and keeps a close eye on him, lest he meddle too much with her plans. She has a fondness for Uncle Rodolphe, merely because of his deep understanding of their shared philosophy. She is quite pleased with Jocelyn's dedication and sees in the woman someone of her own heart, though subconsciously she is somewhat threatened by this and so isn't as affectionate towards the woman as she might be.
Of the Prejeans, she is generally on good terms, but tends to interact with them with an eye towards good breeding stock rather than on a personal basis, which tends to put them off a bit when dealing with her. She is growing quite annoyed, however, with Ida's presumption and has complained to Jean-Michel about it, though he is oddly retiscent to do anything about it. She suspects he may even go so far as to forbid her setting Gui and Gil on her, which has prompted one of the rare occasions when she questions his judgement.
She is respectful but wary of the New Orleans kindred. She thinks of them as allies, but not particularly good ones and certainly not on the same level as her family. She fully supported the first two Sabbat Civil Wars and is somewhat disappointed that they didn't result in a more decisive advantage for the Tzimisce.
She has a deep and abiding hatred of Old Pete, the Gangrel squatter in Alexandria. During the Civil War, he wiped out an entire branch of her family based in that town, including one of her two only childer, Herbert. Since then, she has been making intricate plans to destroy the elder Gangrel in the most painful, prolonged way possible. Most of the rest of the family consider this one of her primary hobbies and encourage it as a worthwhile distraction from her usual obsession.