Venerable Age: You were imprisoned shortly after reaching 10th level. The time between when you achieved 10th level as a mature adult through to today has accumulated the number of years necessary to have become Venerable. Indeed, Elves would be considerably older still than anyone else. No skills were learned in that time, nor XP gained so INT wont affect skill point acquisition. I don't believe I've enabled any of the source books which would enable an ageless or otherwise unaffected character.
Multiple Psions - it hadn't occurred to me that people would prefer DarkSun! heh... that'd be wicked - another time perhaps. Yes, there can be multiple similar classes, etc., as this is a prison and not some road-side bar seeking adventurers of a certain make a model to form a party.
FR Campaign Setting source book - As we're doing Forgotten Realms, I'll edit the list of allowed resources to include: FRCS & Faiths and Pantheons.
Wealth - There is no need to detail equipment. You've likely accumulated your fair share of treasures, land holdings, trinkets, and baubles in the days before you were incarcerated for whatever it was that you did. Some of them were likely rather nice and shiny, too! What has come of them in the passing of decades?! IF you want to detail this separately, by all means do so.
Captured - How, when, where, why (etc., ad nauseam); These details are for you the player to incorporate into your fluff. I'm not talking down-feathers or cotton here. The entity responsible for your imprisonment may still be available for retribution once you make good your escape! This entity should be at least moderately powerful and/or a regime of some sort with interests in keeping you imprisoned rather than martyring you to a cause. Whether it be revolt against a local Dark Lord, or at the hands of a sinister Guildmaster or what have you; the imprisonment need not be just. Heh - maybe you were just aiding and abetting or a mere accomplice to someone of higher and mightier status!? All this is yours to create.
Relationships - It's hard to build a decent one in prison. It's not just the attitude of the imprisoned so much as the guards discouragement. Knowledge of one another is one thing, and limited at best. Knowing each other just wouldn't be possible, nor seeing faces nor hearing voices above a whisper.
The Unasked Question: The Prison - Lastly, the prison itself is obviously designed to thwart various key features including arcane and divine magic, psionics, and supernatural abilities. The effect is such that while you're imprisoned, you've little more than your skin.
Hope that takes care of everything for now. I see I've 3 interested at this time?
Ion Kired
Kaelyn
Steelight
Works for me. I'd be open to a few more at most.