Sad Cat Dance - Gwen's Sad Cat Dance

To this day, I still don't understand how Gwen and Raven became associated together in fanart and fanfiction.
Is it them both being magic-using young girls most commonly associated with late-2000's Cartoon Network? Because that's way too broad a description (Cartoon Network had quite a few magic-using young girls during that era), but I can't think of another connection.

hey buddy, they're cartoon characters, they aren't actual minors