Enemies by Svetlana Chmakova

Felicity's sure she's going to do something big. Exactly what is still a mystery, but she'll figure it out. Her sister, Letty, teases felicity that she never finishes stuff, but that's just because Letty is so perfect. Still, life is good with plenty of friends drawing with the art club and playing games with her buddies keep her busy. But when she decides to join a contest to show Letty that she can get things done, felicity begins to wonder if friends becoming enemies is easier than she thought. Are they really enemies, though. What does it even mean to be enemies. And who is it that she needs the most on her side.