Hiro would be determined to save the kidnapped member. He'd immediately start analyzing the situation, using his intelligence to figure out where they might be held. Baymax would be concerned for the safety of the kidnapped character and would follow Hiro's lead. GoGo would be angry and ready to take action, using her speed to quickly track down any leads. Wasabi would be a bit more cautious but still committed to the rescue. Fred would probably be coming up with wild but potentially useful ideas on how to save their friend.
Well, Hiro's reaction would be a mix of fear and determination. He's lost a lot before, and he won't let it happen again. So he'd be the driving force behind the rescue operation. Baymax, being the caring healthcare companion, would be constantly checking for any signs of harm to the kidnapped character, even from a distance. GoGo's anger would fuel her search, and she'd be impatient with any delays. Wasabi would be nervously trying to keep everyone in line while they plan. And Fred, he'd be the one to try and lighten the mood a bit while still being serious about the rescue, like making superhero - themed jokes.
Waverly would be extremely panicked. She'd probably immediately start looking for any clues around the place where Nicole was last seen. She might also call in all their friends and allies for help, not wanting to waste a single moment.
All Might would be furious. He would see it as his failure to protect Izuku. He would probably mobilize all the resources he has, both in his hero form and his connections in the hero world, to rescue Izuku. And he would be blaming himself all the while for not being there when Izuku was kidnapped.
Sakura would be extremely worried. She would probably try to gather the other members of Team 7, like Sasuke and Kakashi, to go after them. Sasuke might be a bit more hesitant at first, but his loyalty to Naruto would eventually make him join the search. Kakashi, on the other hand, would be more strategic. He would try to figure out Minato's motives first and then plan the rescue mission accordingly.
Hermione would be extremely worried and would start researching like crazy to find out where Dumbledore has taken Harry. She would probably suspect that something is not right with Dumbledore and would try to convince Ron to help her. Ron, on the other hand, would be initially shocked but then would be ready to go on a rescue mission with Hermione.
Max would likely be initially shocked but then quickly start looking for ways to outwit his captors. He'd be making mental notes of everything in the room, like the layout, any possible exits, and what the kidnappers look like.
At first, Kagome is likely to be angry. She's a strong - willed character, so being kidnapped goes against her nature. She would probably struggle and try to escape immediately, yelling at Koga about how wrong his actions are.
Tadashi himself, without his memories, would be confused. He'd see all these people who seem to know him well but he doesn't recognize them. He might feel a bit scared and out of place. As he starts to interact with the others more, he'd slowly form new relationships with them while they're trying to bring back the old ones. There could be some really interesting character dynamics as everyone adjusts to this new situation.
If Hiro was kidnapped in a Big Hero 6 fanfiction, the emotional aspect of the story would be amped up. His friends would be filled with worry and determination. They'd have to dig deep within themselves to find new ways to use their powers. For example, GoGo might have to push her speed limits even further. And Baymax would be constantly updating his search algorithms. The story would be filled with tension as they race against time to save Hiro.
Hiro would probably be a bit awkward at first but then really excited. He'd see it as a new addition to their 'family'. Baymax would be very practical, constantly monitoring her health and giving advice on proper prenatal care. GoGo might be initially surprised but would quickly become supportive, like a tough - love sister. Fred would likely make a lot of jokes about it at first but then also be there for her. Tadashi's memory could be a source of inspiration for them all to support Honey Lemon during this time.
Naruto would probably first try to fight back. He's not the type to just go along with being kidnapped. He'd likely use his Shadow Clone Jutsu to create a distraction and try to escape.