Surrogate Sister, Bottom to Blister

 Rumors of a mysterious lake monster have gripped Canterlot, and Rainbow Dash agrees to take Scootaloo out on a search. But when the younger girl heads out early on her own, and doesn't even bother with a life jacket, she finds out that maybe her dream of getting Rainbow to treat her like a sister isn't quite as perfect as she'd hoped.

Sunset thinks the little brat got off easy, and should be glad Rainbow wasn't using the kayak paddle.