The other characters' reactions would be quite diverse. For instance, the reindeer Sven might sense that something was wrong with Kristoff's mood due to Elsa's kidnapping and nudge him in the right direction during the search. Some of the minor characters in Arendelle, like the townspeople, might be in a state of panic, fearing that Pitch would come for them next if he could kidnap Elsa so easily. Meanwhile, any magical creatures in Elsa's ice palace, like the little snowgies, could start acting erratically, as if they knew their creator was in trouble. And the water spirit Nokk, if it had a connection to Elsa, might try to find her by following any traces of her magic that Pitch left behind during the kidnapping.
Well, Anna would be frantic. She'd immediately set out to find Elsa, not caring about the danger. She might even team up with the Guardians without hesitation. Kristoff would be right by Anna's side, using his survival skills to try and track down Pitch's location. Olaf, being the innocent and loving character he is, would be heartbroken. He might try to cheer Elsa up from afar by singing or reminiscing about their good times, hoping it reached her somehow. The trolls, if they found out, would offer their wisdom and perhaps some magical aid to help in the rescue of Elsa from Pitch's clutches.
One possible plot twist could be that Pitch kidnaps Elsa not for his own gain directly, but to use her as a bargaining chip with the other guardians. For example, he might demand that the guardians give up their powers in exchange for Elsa's safe return. Another twist could be that Elsa discovers a new power within herself while being held captive by Pitch. Maybe her fear and the dark environment somehow unlock a power that is related to shadow or ice in a new way. And a third idea is that Pitch kidnaps Elsa because he realizes that her powers are a key to unlocking a greater power source that he wants to control, but Elsa manages to resist his attempts to use her in that way.
Anna could be the one to save Elsa. After all, she has proven herself brave and determined in the original story. She would stop at nothing to rescue her sister from Hans's clutches.
Naruto would be extremely enraged. He would vow to rescue Sakura no matter what. He would immediately start gathering his friends and form a rescue team. Sasuke, on the other hand, might initially seem more reserved but would also be determined to get Sakura back. He would use his Sharingan skills to track Madara.
Another theme is the idea of isolation. Elsa has been isolated because of her powers, and Pitch is often seen as an outcast in the world of good. Fanfictions may explore how they deal with their loneliness and whether they can find understanding in each other.
There might be. Fanfiction writers can come up with all sorts of creative and unexpected pairings. However, it's also possible that this particular pairing is not very common. It depends on how popular the idea of Elsa from 'Frozen' and Pitch Black from 'Rise of the Guardians' crossing over in such a romantic way is among the fanfiction writing community. You may need to dig deep into different fanfiction categories and tags to find it.
One common theme is the power struggle. Since both Elsa and Pitch have strong and distinct powers, many fanfictions explore how they deal with each other's powers. For example, Elsa's ice powers might be a counter to Pitch's nightmares or vice versa.
One possible plot in this fanfiction is that Hans kidnaps Elsa not just for power or revenge, but because he is being controlled by some dark magic. He takes Elsa to a remote location where she has to fight not only Hans but also the source of the dark magic to free herself and save Arendelle. Along the way, Elsa might discover new aspects of her powers that she didn't know before.
Ron would be furious. He would immediately start looking for Ginny and would probably want to confront Harry without thinking. Hermione, on the other hand, would be more rational. She would try to figure out why Harry would do such a thing and look for clues. The Weasley parents would be extremely worried and would likely reach out to all their contacts in the wizarding world for help.
The villagers would be in an uproar. Naruto is a hero to them, and the idea of him kidnapping Hinata would be shocking. Some might immediately assume the worst and call for his capture. However, those who know Naruto better, like Iruka - sensei, would try to understand the situation first. They would look for reasons behind Naruto's actions and try to find a way to resolve the issue without causing too much harm. Konohamaru, who looks up to Naruto, would be deeply confused and conflicted. He would want to believe that Naruto has a good reason, but at the same time, he would know that kidnapping is wrong.
Naruko herself would probably be shocked at first, but then she would start trying to reason with Sasuke. She would ask him why he's doing this and try to make him see that whatever he's thinking is wrong. She's a strong - willed character and wouldn't just sit there passively.