Wow, suprising to see so many that didn't care for Sion. In my opinion, Sion is a character that was completely amazing, and his storyline cannot end in KOTOR 2, I think he was far more clever than he was given credit. HE salive, no doubt about it, I just didn't buy the whole, glad to leave this place at last ending, the power of the darkside cannot be so easily undone. He exacted his final vengeance on Traya, by allowing her to fall at the hands of the Exile, the thing she loved most. Sion is out there, and I believe he'll make a sweeping return in the next game.....if they ever make one lol. But I wouldn't be the least bit surprised to see him appear in future EU fiction, games or literature, because there is a whole lot of story to examine there. Any other big fans of Sion, check out my fanfic in Coruscant Entertainment district called Darth Sion: A legacy Of Pain..........its on either page 7 or 8.
"Have you come here for answers? There are none. The call of Korriban is strong, but it is the call of the dead. It is fitting you came here."
"The failure is yours, no longer does your voice whisper within my skull, no longer do I suffer beneath teachings that weaken us, and now you run in search of the Jedi. They are all dead....save one, and one broken Jedi cannot stop the darkness that is to come."