I just finished the game, and reran the end sequence several times, and tried different conversational paths with Kreia. No matter what I do, I seem to end up wandering off in search of Revan, which, it appears, is a "Dark Side" ending? At least, that's what the Game center Achievment declared. I expected tthe ending to involve re-trashing Malachor V with the "Shadow Mass" thingie, but that never comes up as an option. My character is so lightside-aligned it hurts my eyes to look at him, but I seem to have no control over the ending. Am I missing something? Thanks, if anyone can clear this up.

strange,it should come up different options like going back into exile\stay there to teach others\leave someone to teach others and give "answers" to those will come there.
to destroy Malachor you need to be LS and have not the line "you have failed me" from Kreia.