Hey, you're reading the description!

Hopefully, Rain and Sunny look young and different enough here as kids. Sunny liked rabbits as a kid, which is where the little nickname Sunny Bunny comes from, so I just gave her some rabbit clothes. Rain's got the dress that I described her having in Rain and Shine, which is my decent-at-best "origin" story for Rain and Sunny.

If you can't tell by the last panel it's heading toward extreme fluff territory.