My Little Pony LI: FE

[Lix Lorn]

Which means you can't be the new final boss, because presumably you are already defeated.

However, there is the Magus precedent.

Spoiler

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Which means you should be available as a powerful ally, if not main character.

...hmm.
If it's about fics being darker, I have an adaptable backstory. I can start out as angstylix, and as the game progresses, I stop using dark magics and go back to cuddlesexy magic. :3