I thought about how I liked to play "Little Mermaid" when I was little by wrapping a blanket around my legs, and I've heard how other girls did that too. But then when a lot of girls get to high school, there's a different attitude. Here's a girl playing mermaid and her older sister. 

Reference: I wanted the older sister to be into super heavy makeup and looking cute. In my sketch, she's sititng on her bed at her bedside table-turned-vanity.

For the little sister, she is rambunctious and likes bothering her older sister: 

Looking forward to everyone's feedback!