Dash spends a whole day with her little sister Scootaloo.

In the awakening of a giant snowball that Equestria has ever seen thrown by yours truly, causes Scootaloo to be pushed through the freezing water. Rainbow Dash dives in risking her own life to save her little sisters life. She now realizes it's a matter of life or death for both of them. She realized that just how important Scootaloo really is in her life.....

and why she doesn't want to lose her either.

Thanks for the cover art!: http://otakuap.deviantart.com/ Credit for cover goes completely to Otakuap!