Mistystorm's story:
Me and my sisters (Lily and Flight. I was just Misty) were born as rogues. Our father had gone hunting one day and never came back.
One day, while our mother was hunting, me and Lily (Flight, the more well-behaved kit, stayed behind) went exploring. When our mother came back, we were still gone. Flight told her that we had left the den out of boredom, but that she had been a good kit and stayed right where her mother had said too. When our mother found us, we were in trouble with a fox. Our mother lost her life saving us.
NOOOO!!!!!! D: 
A NightClan patrol showed up while we were crouching by her body, wondering what was wrong with her. They offered to take us in, but we protested, stating that our sister Flight was still at the den, after we had recovered enough from the grief and denial that our mother was dead to tell the strange new cats about her. The patrol went to find Flight, but she wasn't at the den. It started raining, and her trail was lost.
Misty and Lily were accepted into the Clan by the leader, Stormstar. When we grew up I became Mistystorm, and Lily became Lilyblossom, a full-fledged medicine cat. The instant we arrived in NightClan's cave as kits, we became best friends with Stormstar's daughter and future deputy, Mosskit. Stormstar died, and Mosskit (Now Mosswhisker, of course) became the leader, now known as Mossstar, and I became her deputy. :)
A while later, at the SilverClan Gathering, I met a cat that looked just like me and Lilyblossom's long-lost sister. I talked to her, and discovered that it really was her and that she had joined SilverClan. We were both overjoyed, but neither of us knew that SilverClan magic traveled through blood. Later on, me and Lily discovered that we had powers. I could shape-shift. (Lily's power is currently unknown)
So we all met up as often as we could.
Mistystorm, Lilyblossom, and Greyflight, three magical cats, all sisters, with a future no cat could have foretold.