Author's Apology: Basically it's a kind of origin story for Atris. Familiarity with the events of the Great Sith War as seen in the Tales of the Jedi comics is helpful, but not essential.
First uploaded to the Star Wars Fanon Wikia on July 21, 2021. Rating's what it is for violence; if I'm overestimating it, let me know.
A shout-out is in order to my (if I may so presume) colleague Ahsurika, whose story Forgotten inspired me to experiment with the present tense.
- MPK
July 25, 2021 (Feast of St. James the Great)
In the years leading up to the onslaught of Darth Revan and the Lords of the Sith, the woman known only as Atris was ranked among the wisest and most influential Jedi of her time. Having first come to prominence as an outstanding scholar and historian, she was remembered also as a zealous reformer, and her reputation was further amplified by her close association with other exceptional Jedi, including Nomi Sunrider and her daughter, Vima. It was also said that Atris's rhetorical skill was matched by her ferocity with the lightsaber, though few indeed could say that they had ever seen her in battle.
Yet four decades before Revan's disappearance and the rise of the Sith Triumvirate, Atris was only one of many talented apprentices hoping to join the ranks of the Jedi Guardians. Long before being menaced by the Mandalorian Neo-Crusaders or the armadas of the Star Forge, the civilized galaxy knew peace under the guiding hand of a benevolent Galactic Republic and a Jedi Order ten thousand strong.
Such were the times into which Atris was born. But as destiny would have it, she was also born into the end of that era and the beginning of a new one, the outset of which would be marked by the heroism of the Sunriders, the tragedy of the Qel-Dromas, and the machinations of the renegade Exar Kun. Having succumbed to the allure of the dark side, Kun spread his taint to other Jedi, inducing a handful of suggestible Padawans to join him in a new Sith Brotherhood. Though the ensuing conflagration of the Great Sith War would be eclipsed in the times to come, its fires brought much suffering and ruin, and they left no Jedi untouched.