>>23491098
Not the same guy, but if I were running it I'd go with an alternate continuity, just to get away from all the pre-established characters. Sozin and Roku both died on the volcano, the fire nation never attacked the rest of the world, Avatar Katara is currently training with the Fire Sages, Aang having died aged 90-something, that sort of thing. Frees you up to have your own story without interacting with anything but the core of the setting. Might bump into Fire Lord Iroh and his son, or Toph (who would still be Toph), or the Kiyoshi Warriors, or the Dai Lee (still the secret police of the Earth Kingdom, but not supressing news of the war anymore), but you don't have to use any of them. They might not be all that important.
Oh, and if I could play anything, I'd play Rogue Trader. I'd be the captain, I'd have my stupid fast Orion clipper, and I'd Kirk my way across the Expanse. Probably never going to happen.