Another theme is the relationship between Dib and Zim. In many fanfictions, their rivalry either intensifies or takes on a new form. It could be that they have to team up against a new threat that emerged because of the Florpus.
One great 'Invader Zim: Enter the Florpus' fanfiction is 'The Aftermath of the Florpus' on FanFiction.net. It explores what happens to the characters after the events of the movie in a really interesting way.
Often, there's a theme of self - discovery. As Female Zim is a different take on the character, she might be on a journey to figure out who she is in this new form. Also, the theme of adaptation is common. Just like in the original where Zim has to adapt to Earth, Female Zim may have her own unique ways of adapting, whether it's to Earth's environment or to the reactions of the other characters around her. And there's also the theme of power. How does being female change Zim's perception and use of power? This is something that many fanfictions like to play with.
The appeal of 'Invader Zim Gaz x Zim' fanfiction lies in the contrast between the two characters. Gaz is this tough, no - nonsense girl, while Zim is this bumbling alien. When they are paired in fanfiction, it creates a really interesting dynamic that fans love to explore.
A really interesting 'Invader Zim female Zim fanfiction' is 'Zim as a Girl: The Alter Ego'. This story plays around with the idea of Zim having a female alter ego. It's fascinating to see how the other characters react to this new version of Zim. Additionally, 'Female Zim in the Human World' is a great read. It focuses on how Female Zim adapts to human society, with some really funny moments like her trying to understand human fashion and social norms.
A prevalent theme in 'Invader Zim baby fanfiction' is the idea of growth and change. Even as a baby, Zim might still have his grand plans of conquering Earth, but he has to adapt his methods. There's also often a theme of protection. Characters like Dib might see the baby Zim as an even greater threat and try to protect the world from him, or in some cases, protect the baby Zim from other threats in the universe.
One common element could be the suffering of the main characters like Zim or Dib. Maybe Zim fails in his invasion plans in a particularly painful or humiliating way for him, which is a form of hurt. Or Dib could be constantly ridiculed and isolated, which causes him emotional pain.
An interesting Invader Zim fanfiction could center around an alternate universe where Zim is actually a good guy sent to protect Earth from other threats. Or it could be about Zim and Dib getting stuck in a time loop and having to figure out how to break it. You might also consider a story that focuses on the strange and unique creatures in the Invader Zim universe and how they interact with Zim and Dib.
One common theme is the struggle for power. Zim, as a vampire, often tries to gain more power, whether it's over Dib or in the vampire world itself. Another theme is identity. Zim has to figure out who he is now that he's a vampire. Is he still the same invader or has he changed?