In a Naruto and Phineas and Ferb crossover fanfiction, perhaps the characters would team up to face a common enemy. Naruto's combat skills combined with Phineas and Ferb's out - of - the - box thinking could lead to some really interesting scenarios. For example, Naruto could use his Rasengan while Phineas and Ferb create a giant contraption to either help or hinder the attack. Also, Isabella might be fascinated by Naruto's headband and ask him all about his village.
Well, Naruto could visit the world of Phineas and Ferb. He might be really confused by all the crazy inventions that Phineas and Ferb create every day. And he could show them some of his ninja skills, like running up trees or making clones. Maybe Ferb would be interested in learning some ninja techniques to add to his own knowledge of building things.
One possible plot could be that Phineas and Ferb build a super - advanced lightsaber - like device in their backyard. Meanwhile, the Star Wars characters mistake it for a new Sith weapon. Then, Phineas and Ferb get caught up in the Star Wars universe and have to use their creative skills to help the Jedi defeat the Sith.
Well, it could be about how Phineas tries his best to take care of Ferb. Maybe he builds some crazy contraption to make Ferb feel better, like a super - advanced bed that can do all sorts of things to ease Ferb's illness.
Well, perhaps in the fanfiction, Phineas gets mad because Ferb accidentally ruins one of their big inventions. Maybe they were building a huge roller coaster and Ferb made a miscalculation that made the whole thing collapse. Phineas, who is usually calm and positive, gets really frustrated and yells at Ferb for the first time.
One idea could be a crossover with 'Kim Possible'. Phineas and Ferb could use their inventive skills to help Kim in one of her missions against Dr. Drakken. Maybe they create some high - tech gadgets for her. Another idea is a crossover with 'The Simpsons'. The boys could visit Springfield and get involved in some wacky adventures with Homer and Bart. They might even build an amazing contraption in the Simpsons' backyard.
Well, maybe the plot could involve Mom getting accidentally involved in one of Phineas and Ferb's wild inventions. For example, their latest gizmo could transport Mom to a strange parallel dimension where she has to team up with Phineas and Ferb to find a way back home. Along the way, they might encounter some of the wacky characters from both universes and have to use their combined creativity and skills to overcome various obstacles.
I think Naruto would be the most interesting. He has such a unique background and abilities. His ninja skills and his journey to become Hokage would contrast so much with the laid - back, creative world of Phineas and Ferb. He could bring a whole new level of action and adventure to their world.
One possible plot could be that someone ruins Phineas's big invention project. Maybe Doofenshmirtz creates a device that accidentally targets Phineas's backyard and destroys all the materials for his amazing new roller coaster. This makes Phineas really mad and he decides to go on a mission to get back at Doofenshmirtz. Ferb tries to calm him down but Phineas is too angry at first. Then they end up working together to not only fix their project but also teach Doofenshmirtz a lesson about being more careful with his inventions.
Perhaps Phineas gets diarrhea right before a big event they were planning, like a huge backyard invention showcase. This causes chaos as they have to delay the event. Meanwhile, Candace, thinking this is a perfect opportunity to get the boys in trouble, tries to call their mom. But Ferb manages to keep her at bay while also taking care of Phineas.
One possible plot could be that Phineas gets dysentery right in the middle of one of his big summer projects. His friends and family then have to figure out how to take care of him while still trying to keep their daily adventures going. Ferb might take on more of the leadership role in their projects while also looking after his brother.
Definitely Doofenshmirtz. He could mess with one of Phineas and Ferb's inventions in a way that really ticks Phineas off. Like he might use one of his -inator devices to turn their amazing flying machine into a pile of junk. Phineas would be furious and would then set out to fix it and get revenge on Doofenshmirtz.