Two sides of one crown

And yep, not Luna only have dark side)

Celestia also can have dark thoughts you know)

Plus I think that any powerful alicorn, who can to destroy everything, has thoughts about it time to time^^

- One kingdom two rulers?! Seriously?! This Sucks! You Sucks!You are weak! Just let me free and I will settle it! I... khm... we will rull all this world!- works makes me crazy, I need a break.