One possible plot could be that Zim and Dib from 'Invader Zim' somehow end up in the 'Futurama' universe. Zim might see the advanced technology in Futurama as a new opportunity to take over a planet. He could mistake Planet Express for a major power center and try to infiltrate it. Dib, on the other hand, would be excited to explore this new world and might team up with Fry, Leela, and Bender to stop Zim's new evil plan.
Maybe the Professor in 'Futurama' accidentally creates a portal that sucks in Zim and GIR from 'Invader Zim'. Zim thinks he's landed in a new planet to conquer. However, the Planet Express crew initially mistakes him for some sort of strange alien experiment gone wrong. Bender might be jealous of GIR's unique design and they get into a series of comical battles. Meanwhile, Dib follows Zim through the portal and tries to convince the Futurama characters of Zim's true intentions.
Zim and Bender would be a really interesting interaction. Zim is this over - confident alien bent on world domination, while Bender is a self - centered, kleptomaniac robot. They could start off by trying to out - do each other in terms of causing chaos or stealing things. GIR and Fry could also be a fun pair. Fry's simple - mindedness would match well with GIR's random and silly behavior. They could get into all sorts of comical situations together, like accidentally starting a food fight in the Planet Express cafeteria.
Well, it could be really wild. Maybe Steven could use his gem powers to try and stop Zim's crazy plans for world domination. Zim, on the other hand, would probably be super confused by Steven's powers and the whole concept of gems.
It could be about Zim finally succeeding in his plan to take over Earth. Maybe he discovers a new weakness in the humans that he exploits.
There could be all sorts of fun scenarios! Maybe the Doctor lands in Invader Zim's universe and has to help him deal with some crazy alien threats.
Well, it could be about a space girl who encounters Invader Zim. Maybe she tries to stop his evil plans on Earth. She might use her special powers from outer space to outwit Zim and his various gadgets.
One possible plot could be that Naruto and his friends somehow get transported to the Futurama universe. Maybe they're chasing after a rogue ninja who has a device that can open portals to different dimensions. In the Futurama world, they team up with Fry, Bender and the rest. Naruto could teach them some ninja skills, like how to stealthily move around, and in return, the Futurama crew could introduce Naruto to some of their advanced technology, like the Planet Express ship. It would be a really fun mix of the two very different universes.
The clash of different aesthetics. Jhonen Vasquez has a very distinct style in both JTHM and Invader Zim. When you cross them over, you get a really unique visual and narrative blend.
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.
One idea could be a crossover with 'The Simpsons'. Zim could try to infiltrate Springfield, thinking it's a key Earth location for his invasion plans. Maybe he mistakes Homer for a powerful Earth leader and tries all sorts of wacky schemes to take over the town through him.
One interesting Gir crossover Invader Zim fanfiction could be one where Gir teams up with Dib to stop some new alien threat that neither Zim nor the other regular villains can handle. In this story, Gir's unpredictable and silly nature might add a lot of comical elements to the usually tense relationship between Dib and Zim.