Luck: It's just amazing, isn't it? At their respective births, Sunset Shimmer and Twilight Sparkle had the same luck, they were both born with the same capabilities, thirst for knowledge and magic potential. Yet they ended up in two completely opposite paths.

Fate: Indeed. They are both living proof that regardless of what lot in life a pony might have had, it is their personal choices that led them into their current destiny.