Talk:Twilight Sparkle/@comment-24585407-20140518054445/@comment-166269-20140520063310

None of these are conclusive evidence for the immortality of any character.

We know very little of the sisters' personal history: not if they were born alicorns; not who - or what - their parents were; not if they've always had their powers or gained them at some point (we do know they didn't always control the sun and moon, but that's all we know); etc. We don't know if they are truly immortal or merely long-lived, or where their longevity comes from (though that's stopped exactly no one from coming up with their own ideas).

Discord is shown to be able to largely ignore the laws of reality, morphing his body into arbitrary forms and warping reality around him to suit his tastes or purposes. It should come as no small surprise that he can survive apparent decapitation. Again, though, not evidence of immortality: the animal kingdom is rife with examples of animals that can survive indefinitely with most or all of their head removed; in practice the thing that kills them is starvation or thirst, and if they are kept fed and watered, can live quite happily to the ends of their natural lifespans. And his abilities are shown to be tied to his magic when Tirek steals it from him.

Tirek was in Tartarus: that plane could conceivably keep its occupants alive so as to ensure they serve out their full sentence, which would have trivially allowed him to survive the millennium. We can't decide either way in this case, because both explanations are conjecture.

Nightmare Moon was not "shattered" to restore Luna, she was Luna. About as close as the Elements of Harmony would have gotten to destroying NMM in that case would have been to destroy the nightmare itself, and unless I'm mistaken, the comics have shown that even that didn't happen (Nightmare Rarity says hello).

And lastly, the Elements of Harmony/Rainbow Power: they have never been shown to outright destroy a character, regardless of that character's alignment, goals, intent, etc., with the singular exception of Sombra, who was implied to be beyond redemption (assuming there was anything left of the original pony to begin with by the time of the events of the Crystal Empire episodes).

There has not yet been conclusive evidence one way or the other on the immortality of any character.