In a crossover fanfiction, the interactions would be really interesting. Ford, if he were involved, would be very intrigued by the animatronics. He might study them to see if they are related to any of the other interdimensional beings he has encountered. Dipper would be the voice of reason, warning everyone about the potential danger. Mabel would try to find the good in the animatronics, perhaps believing that they are just misunderstood. Soos would be the comic relief, making jokes about the animatronics' appearance. Wendy would be the tough one, ready to fight if necessary. The animatronics themselves might be confused by the Gravity Falls gang. The ones that are more aggressive might see them as a threat, while the more docile ones might be curious about these new visitors.
Mabel and Hilda would be fast friends. They both have a love for the strange and wonderful. Mabel would be excited to show Hilda her sweaters and all the cool stuff in the Mystery Shack. Hilda would share her adventures in Trollberg with Mabel. They might even come up with some new and crazy ideas for adventures together, like having a slumber party in a haunted forest. Wendy would probably be a bit more aloof at first, but as she gets to know Hilda, she'd start to warm up and they could go on some more adventurous outings, like climbing a really tall mountain in Hilda's world.
Well, I think Lance would be really intrigued by Mabel. He'd probably be impressed by her colorful sweaters and her positive attitude. Mabel, on the other hand, would be excited to meet a real - life space hero like Lance. She might even try to set him up with one of her friends in Gravity Falls.
Bill Cipher would be a major wildcard in their interactions. If he were to cross paths with the Winchesters, he would likely try to manipulate them for his own amusement. He might offer them false information or try to pit them against the other characters in Gravity Falls. The Winchesters, being used to dealing with devious creatures, would have to be on their guard and figure out a way to outwit Bill while also trying to solve whatever mystery has brought them to Gravity Falls in the first place.
Mabel would be excited to meet the Winchester brothers. She might try to get Dean to tell her all his hunting stories and would probably try to knit them some cool accessories. She could also introduce Sam and Dean to Waddles. Dipper would be a bit more cautious around them at first, but as they started working together, he would respect their skills and knowledge. The characters would need to learn to trust each other quickly since they come from different worlds but are facing similar threats.
The characters' interactions would be really interesting. For instance, Ford from Gravity Falls, being a scientist, would be fascinated by the magic in Equestria. He might try to find a scientific explanation for it. Fluttershy would be a bit shy around the Gravity Falls humans at first, but would soon open up. The ponies' positive and friendly nature might have an impact on the more cynical characters in Gravity Falls, like Soos. He could learn a lot from their friendship values. Meanwhile, the Gravity Falls gang could introduce the ponies to new things like s'mores and camping.
One idea could be that the characters from Gravity Falls end up in the FNAF world. Dipper might be intrigued by the mystery of the haunted animatronics and try to solve it using his journal. Mabel could befriend the more friendly - looking animatronics, like Chica, and try to make them cute accessories. Another plot could involve the FNAF villains getting loose in Gravity Falls and the Pines family having to use the town's unique magic to stop them.
Definitely Dib and Dipper. They are both curious and into the strange and supernatural. Dib with his alien - hunting skills and Dipper with his knowledge of the Gravity Falls mysteries would make a great pair.
Some animatronic hybrids in fnaf fanfic might interact with the original animatronics in a hostile way. They could see the originals as a threat to their existence or as inferior beings. For example, a powerful hybrid might try to dominate the area where the original animatronics are, leading to conflicts.
The characters would likely have a mix of admiration and friendly rivalry. For example, the cool and collected protagonist of Persona 5 might be intrigued by the more laid - back nature of the Persona 4 protagonist. Meanwhile, the Persona 3 protagonist, with his more somber and serious demeanor, could initially seem a bit intimidating to the others. But as they get to know each other, they would start to bond over their shared experiences of fighting Shadows and protecting their worlds.
The 1987 Turtles would probably be very curious about the more serious and intense 2003 Turtles. They might crack jokes at first to ease the tension, while the 2003 Turtles could be a bit annoyed by their silliness. But as they face challenges together, they'd start to respect each other. For example, when fighting Foot Soldiers, the 1987 Turtles' acrobatic and fun - loving fighting style could complement the 2003 Turtles' more strategic and brutal combat.