Character interaction is also a big theme. The different personalities from both shows collide. You might see David from Camp Camp trying to keep everyone positive in the face of Gravity Falls' oddities, while Dipper is trying to figure out how to use Camp Camp resources to help in his mystery - solving. It's really interesting to see how they play off each other.
Another option is to check out some fanfiction communities on Reddit. There are subreddits dedicated to both Camp Camp and Gravity Falls where fans might share or discuss their 'camp camp meets gravityfalls' fanfiction ideas or links to their works.
I haven't actually read this specific fanfic. But generally, if 'camp camp' meets Max's shitty parents in a fanfic, it could be a really interesting exploration of the characters. It might show how Max's relationship with his parents affects his experiences at camp, and how the camp environment in turn influences his view of his family situation.
I haven't read this fanfic specifically. But generally, in a 'camp camp meets max's shitty parents' fanfic, it might explore how the camp camp environment and characters interact with Max's difficult family situation. Maybe it shows how the friends at camp support Max when facing his shitty parents, or how Max's experiences at camp change his perspective on his family.
A really cool plot could involve a prophecy that predicts the joining of the two camps. This could lead to some initial mistrust and rivalry among the demigods, but as they face common enemies and challenges, they start to bond and learn from each other. For example, the Camp Jupiter demigods could teach the Camp Half - Blood ones about Roman battle strategies, while the Camp Half - Blood demigods could show their counterparts some of their more unorthodox Greek magic.
One idea could be a quest that requires demigods from both camps to work together. Maybe they have to retrieve a powerful artifact that's being guarded by an ancient monster. The demigods from Camp Half - Blood could use their unique skills like Percy's water - based powers, and those from Camp Jupiter could contribute their Roman - style combat and discipline.
One possible theme could be family dysfunction. Since Max has shitty parents, it's likely that the fanfic will explore how a broken family affects a child like Max. Another theme might be the search for acceptance. At camp, Max may be looking for the acceptance he doesn't get at home.
No, it's not really normal in the traditional sense. Fanfiction is something created by the fans outside of the official story. But in a very creative or experimental take on the Camp Camp concept, it could be a fun and unique idea.
Reyna from Camp Jupiter would also be a great character to focus on. She's strong, intelligent, and has a lot of leadership experience. In a fanfiction where the two camps meet, she could represent the Roman side well, and her interactions with the Greek demigods would be full of potential for conflict and cooperation. For example, she might initially be skeptical of the more laid - back Greek approach to things, but come to appreciate it as they work together.
Percy Jackson is an obvious choice. His abilities and leadership skills from Camp Half - Blood would be a great addition to any story where the two camps meet. He could interact with the Roman demigods, maybe even have some friendly rivalries with the strong leaders from Camp Jupiter like Jason Grace. His loyalty to his friends and his sense of humor would also add a lot to the story.