my idea, which anyone can use or part of it is simple,
twilgith and sunset are best friend as filly,
sunset become the princess student
twilight end up the student of a lich like who work for the princess, think of Kel'Thuzad style lich and mind set, who teach twilight a lot of what he knew. this would include twilight being raise by him out side of the country, only to return as a moraly gray necromancy/dark magic user who willing to do questionable thing to get the job done.
she still best friend with sunset who take more of a light base paladin mindset.
twilight would be baddass, slight op not caring about overall damage or mental state of others in order to keep everyone safe. she would still be an element, be it magic or one of the others, living with sunset in ponyville,

Sounds interesting will read if it's not anthro.

6939655
Reminds me of fic called Split Second in that one it's two alternate versions of Twilight that can talk to each other but it follows a similar General concept

6939655
Interesting. I think I might be able to spin this into a story if I have the time.

6939660
forgot about that story, it was good one

6939686
Too bad the sequel Fic looks pretty dead

6939688
yeap, it was getting good, hate when a fic dies when it get good or end open like,

6939655
But, isn't Kel'Thuzad evil? (I think... I've never played Warcraft.)

7172654
i would say he is evil but he is cunning and intelligent.