Crossovers that involve the Avengers getting lost in the Gravity Falls forest and having to rely on the locals like Soos to find their way out are also quite engaging. It shows the contrast between the high - tech Avengers and the down - to - earth Gravity Falls residents, and how they can learn from each other in such a situation.
The crossovers where the Avengers have to deal with Gravity Falls' supernatural villains are really interesting. For instance, when they face Bill Cipher. It's fascinating to see how the Avengers' powers stack up against such a powerful and otherworldly foe.
Another idea in the fanfiction could be that Gravity Falls has a hidden connection to the wizarding world. Maybe there are witches and wizards who have been secretly living in Gravity Falls for centuries. Dipper and Mabel could discover this connection and start learning magic from them. They could then use their newfound magical abilities along with their existing skills to explore the mysteries of both Gravity Falls and the wizarding world.
One interesting crossover could be the characters from Gravity Falls and Steven Universe teaming up to solve a mystery that involves both the Gem world and the strange happenings in Gravity Falls. For example, Dipper and Steven might combine their knowledge of the supernatural to figure out a new threat.
One interesting crossover could be the characters from Gravity Falls ending up in the world of MLP. Maybe Dipper and Mabel could meet Twilight Sparkle and her friends. They could go on adventures together, like exploring the Everfree Forest in MLP's world. Dipper's love for mysteries might lead him to study the magic in Equestria.
Some crossovers focus on the character relationships. For instance, Wendy from Fairy Tail and Mabel from Gravity Falls could become fast friends. They both have a sense of adventure and a kind heart. Wendy could show Mabel some of her sky dragon slayer magic, and Mabel could introduce Wendy to her world of sweaters and boy bands.
There's also 'Avengers in Gravity Falls'. In this fanfic, the Avengers find themselves in the strange town of Gravity Falls. It's great because it shows how the Avengers would react to the odd creatures and situations there. For example, Thor is really confused by the gnomes at first, but then he tries to fight them with his hammer, which is hilarious.
One interesting Gravity Falls fanfiction could be those that explore the further adventures of Dipper and Mabel after the events of the show. For example, a story where they discover a new mystery in Gravity Falls during their next summer vacation. Another could be a fanfic that delves into the backstory of Bill Cipher and his connection to other characters in a more detailed way. There are also fanfictions that focus on the relationship between the characters, like how Dipper and Wendy's friendship might develop further.
One interesting storyline could be the characters from both universes teaming up to solve a mystery that spans across their respective worlds. For example, Dipper from Gravity Falls and a character from Relativity Falls might work together to figure out a strange phenomenon that is affecting both places.
In some fanfictions, there might be a plot where the Avengers mistake Ben for a threat at first. But then they realize his good intentions when he helps them fight a common enemy. This adds an element of misunderstanding and then friendship, which is quite common and engaging in crossovers.
One interesting crossover could be the Flash from Arrowverse meeting Quicksilver from the Avengers. They could have a race to see who is truly the fastest. Another could be Green Arrow teaming up with Hawkeye for an archery - based mission where they share their different techniques and arrow - making skills.
A possible crossover could involve the technology of Kingsman, such as their fancy suits and gadgets, being integrated into the Avengers' gear. The Kingsman's bulletproof suits and high - tech umbrellas could give the Avengers an edge in combat. Also, the different cultures and protocols of the two groups would create some interesting clashes and comical moments as they try to work together.