A 'friends crossover fanfiction' with 'How I Met Your Mother' could be really fun. Maybe Ted Mosby could be in New York for a job interview and end up at Central Perk. He meets the friends group and starts sharing his stories about searching for love. The different perspectives on relationships between the two shows would create great storylines.
A great idea for 'harry potter and friends crossover fanfiction' is a crossover with 'Narnia'. The magical world of Narnia and Hogwarts have some similarities. Harry and his friends could enter Narnia through a magical portal in Hogwarts. They could help the Pevensie children in their battles against the White Witch. Another option is a crossover with 'The Chronicles of Prydain'. Harry and his friends could journey to Prydain and encounter the magical creatures and challenges there. And a crossover with 'Fantastic Beasts' but in a different way, like the main characters from 'Harry Potter' meet Newt's ancestors and have adventures with them.
A crossover with 'My Little Pony' could also be fascinating. Picture the pastel - colored ponies meeting the cute but accident - prone HTF characters. There could be a lot of confusion as the ponies' magic might not work in the same way in the HTF world. The HTF characters would be intrigued by the ponies' kindness and harmony - based society.
One idea could be that Jerry and Elaine visit Central Perk. They meet Chandler and Joey, and there's a whole mix - up about a couch. Jerry wants to buy it from Joey, but Chandler has some hidden feelings for it. Another could be Phoebe dating Kramer. Kramer's wacky antics drive Phoebe crazy in a love - hate relationship way.
One interesting idea could be a crossover with "Moana". Elsa's ice powers and Moana's connection to the ocean could create a really cool dynamic. Maybe Elsa accidentally freezes part of Moana's ocean and they have to work together to fix it. Another could be with "Tangled". Rapunzel's long hair and her adventurous spirit combined with Elsa and Anna's journey in Frozen 2 would be exciting. Rapunzel could use her hair to help them climb mountains or cross chasms. A third idea is a crossover with "Beauty and the Beast". Belle's love for books and knowledge could help Elsa understand more about her powers and the history of magic in the Frozen world.
One idea could be to explore the friendships in different time periods. For example, how their friendships might have been different during their academy days compared to when they are on missions as adults. Another could be a 'what if' scenario, like what if Naruto made friends with an outsider to the village early on.
One idea could be exploring the backstories of the Smiling Friends characters in more detail. For example, what made Pim and Charlie become Smiling Friends in the first place? Another could be creating a crossover with another popular animated series, where the Smiling Friends have to interact with different characters and face new challenges.
A Rambo crossover fanfiction could involve him crossing over into the Star Wars universe. Rambo's guerilla warfare tactics could be interesting in a galaxy far, far away. Maybe he helps the Rebel Alliance in a ground - based battle against the Empire. Or a crossover with the Predator series. Rambo would be a worthy opponent for the Predator, and the fight between them in the jungle could be epic. Also, a Rambo and John Wick crossover would be intense, two highly skilled fighters on the same side or perhaps initially at odds.
One idea could be a crossover with a modern military setting. The Decepticons could be trying to steal advanced military technology. Another is a crossover with a post - apocalyptic world where they are competing with other factions for resources. A third could be a crossover with a magical realm, with the Decepticons trying to harness the magic for their own evil purposes.
One idea could be a crossover with Naruto. Kakuzu could be sent to the Naruto universe and form an unlikely alliance with a shinobi village to fight a common enemy, like the Akatsuki from his own world turned rogue in the new universe. This would create a lot of interesting character dynamics and battles.
Another option is a crossover with 'The Little Mermaid'. The characters from the descendants could meet Ariel and her friends underwater. Evie might be interested in the mermaid fashion and could design new outfits inspired by the underwater world.