"but I don't see how it serves the story in all." Mostly agree with you here. She doesn't seem to further the plot. She only serves to give Selena/Catwoman some context in terms of who she is as a person, what sort of relationships is she in, who does she surround herself with. It's pretty implied t...

Jen/Holly does serve a purpose. She quietly makes Selena's character look bisexual. Selena is living outside society's rules and playing by her own. Is she good or evil? Moral or amoral? Loyal or disloyal? This is a theme with her character. Add gay or straight to the mix.