I'm still holding in between two concepts- the elan psion might be an interesting foil to traditional arcanists, but I might want to "play along" with the more normal possibilities. So, two capsule concepts:
1. Elan psion (possibly pure psion, possibly aiming for Metamind or Psion Uncarnate). For thousands of years, the elan have dwelled in the remote corners of the world, their small outposts deliberately isolated from the mundane concerns as they pondered the truths of the mind, and of the world around them. From time to time, each outpost might sent forth a lone wanderer or two- perhaps to seek a particular item, or a certain piece of information; but for the most part they were content to dwell apart. But with the Purge gaining strength, even their power and isolation were not enough to shield them. When they could be found, the forces of the enemies sought out these citadels and threw them down- killing the 'mind-mages', destroying their crystals of power, and obliterating every scrap of knowledge they found. But in their anger and ignorance, they failed from time to time... New elan were not born, after all- they were made, grown within crystalline cocoons. To the eyes of the uninitiated, some of these 'unborn' elans looked like prisoners, held within glassy cells, thier minds damaged or destroyed by the mind mage jailers. Suvaria was one such- nearing her 'birth', she was released by the same folk who had just wiped out the rest of her colony. She was at a loss as to what to do, but the conversations of her 'rescuers' spoke of one city left unburnt, where the dark wizards yet lived- and that was where she knew she had to go, to find the secrets of her own past, and to strike at those who had slain her people.
2. Human Beguiler/Warlock (aiming for Eldritch Theurge and using the Fey Heritage feat chain from Complete Mage). Even before the time of the Purge, the fey folk had sensed a change coming, and many of them had begun to retreat from the mortal world. Those few that remained often lived in isolated, inhospitable places- deep dark forests, windswept mountaintops, oases deep in the desert... Wherever they lived, though, they still had some interest in human contact, and some humans still sought out theiir wisdom and magics. The Oasis of Silver Leaves was one such place- the sages and wisewoman of the desert tribes made a yearly pilgrimage to the fey lords and ladies who held court there. Some children were born with such a heritage, and they were often marked for greatness. Sayida was one such child- from an early age, she had a talent for magic, and a keen mind. She was raised to be a wisewoman and a lorekeeper, to serve her tribe. But as the Purge gained strength and support, some of the tribes joined the movement, slaying all of the mages they could find. the few tribes that resisted the call,and resisted the violence of the converts, knew that something had to be done, and they sent some of their few remaining wisefolk to the fabled city of Arcana...
