The Unraveled Rainbow by seraisyre

Rainbow Dash has always been the fastest, the toughest, the one everypony counts on. So when she begins to see strange clouds that nopony else can — dark, flickering reminders of everything that might go wrong — she keeps it to herself. But these aren’t weather clouds. They’re something deeper. Something darker.

As Rainbow quietly unravels, her friends begin to notice. But instead of confronting her with fanfare or force, they do something radical:

They love her quietly.