__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk
Shaak Ti wins, and all you really need to do is make Sion give in, if he doesn't do that, Shaak Ti wins. But he usually does give in if beaten enough times, I don't think it was just because of him thinking that Meetra Surik was Darth Traya's favorite, I think it was the realization that he was beaten several times, and that Meetra was better then him, it shocked him, and... turned him? (I guess???)
Actually, he fell in love with Surik and grew an insane obsession with her. Finally, he just gave in because Surik convinced him to, him only listening because of the aforementioned obsession; she didn't turn him to anything tho.
Sion still can die from normal means, he just comes back, However, his body doesn't heal at all.
After Revan and TOR came out, I feel KotOR 1 and2 characters aren't getting the respect they deserve.
Kreia > Shaak Ti in the force. It took someone of her calibre to break Sion. Not to mention they already had a close relationship with each other (master and apprentice).
I don't think Shaak Ti would have an easy time with Sion and his endurance might be enough to pull out the win.
In a deleted scene, he was able to withstand even Nihilus' drain, so breaking him isn't a trivial task.
If it's to a permanent death, then I see Sion winning, but if it's just to a defeat, then I give it to Shaak Ti. I doubt looking like you "sleep with vibroblades" speaks positively for your combat prowess, Sith Lord or not.
Sion doesn't show combat prowse enough to be above Shaak Ti, only endurance. If we're using deleted scenes, it's probably more likely that rush trained Atton beat him down than not. And really the only thing Kreia has above Shaak Ti is giga-drain. Sion lived because of his invulnerability, not his strength when Nihlus tried to drain him.
Yes, Sion loves Meetra Surik but in an extremely unorthodox way. It's not simple physical attraction or loving her personality. It's the fact that she felt what he felt, an unending pain in the Force. But the final reason why he fell in love with her was not just because of that, that was simply the catalyst. The reason why he loved her was because unlike him she was not only able to cope with her pain but eventually conquer it, something Sion can't do.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."