The comic book heroine D was impersonating was Polaris Girl from (supposedly) back in the 70s/80s. She was also annoyed that J reads comic books because she thinks they're too "babyish." But, at the end of the show, she forgoes going out with Zoe and Julius somewhere (I think it was another comic book convention) and stays in reading up about the heroine she was impersonating.
Author's response
Hey, thanks for all that info I never knew that. Yeah and also Delilah can get pretty jealous of Zoey at times.