Well, perhaps Drago kidnaps Hiccup because he thinks Hiccup is the key to finding a hidden dragon lair filled with powerful and rare dragons. He might believe that Hiccup has some secret knowledge or connection that can lead him there. And then, the story could follow Hiccup's friends as they try to rescue him and in the process, they uncover more about Drago's past and his real motives for wanting the dragons.
One possible plot twist could be that Drago kidnaps Hiccup to use him as a bargaining chip against the dragons. Maybe he wants to force the dragons to submit to his will by threatening Hiccup's life. Another could be that Drago discovers some special power within Hiccup that he wants to harness for his own evil purposes. For example, Hiccup's ability to communicate with dragons might be something Drago wants to use to control all dragons.
In a fanfiction where Drago kidnaps Hiccup, it could start with Drago seeing Hiccup as a threat to his plans of dominating the dragon world. So he takes Hiccup in a surprise attack. Hiccup, while being held captive, tries to reason with Drago, telling him that there is a better way to co - exist with dragons. But Drago doesn't listen. Meanwhile, Toothless, Hiccup's dragon, goes on a desperate search for his friend. Along the way, Toothless teams up with some other dragons who also have a grudge against Drago. They all work together to find Hiccup and stop Drago once and for all.
Hiccup's friends would be extremely worried. Astrid, being Hiccup's closest friend and love interest, would probably be the first to take action. She would gather the other riders and start planning a rescue mission right away. Snotlout might initially be a bit hesitant, but the thought of losing Hiccup would push him to join in. Fishlegs would use his knowledge of dragons to figure out where Drago might be hiding Hiccup.
One possible plot could be that Toothless is under some sort of spell or mind control. Maybe a new villain in the How to Train Your Dragon universe has the power to manipulate dragons. Toothless, being a powerful Night Fury, is forced to kidnap Hiccup. Hiccup, of course, tries to figure out why Toothless is acting this way and how to break the spell.
In a fanfiction scenario, Viggo might kidnap Hiccup out of jealousy. Hiccup has a special bond with Toothless, a very rare and powerful dragon. Viggo, who has always been obsessed with dragons, may be envious of Hiccup's connection. He kidnaps Hiccup to try and take Toothless for himself. He might think that by having Hiccup in his control, he can make Toothless obey him. He could also use Hiccup as a bargaining chip to get more dragons from Berk.
Another plot twist could be that the reader has some sort of power or knowledge that Loki needs. So, instead of a malicious kidnapping, it's more of a strategic move on Loki's part. He might be trying to bargain with the reader to get what he wants, but as time passes, he starts to develop feelings for the reader.
One possible plot twist could be that Aizen has a hidden motive other than just causing chaos. Maybe he kidnaps Ichigo to use his unique powers for some sort of experiment. For example, he might want to extract the power of Ichigo's Hollow side to enhance his own strength or create a new type of Arrancar. Another twist could be that Aizen is being controlled by an even greater force, and Ichigo's kidnapping is part of a larger plan to draw out other powerful characters in the Soul Society.
Well, perhaps the plot of the fanfiction where Sasuke kidnaps the reader could involve a misunderstanding. Sasuke might think the reader is working for his enemies when in fact they are not. As for the story development, it could lead to the reader gradually understanding Sasuke's past traumas and reasons for his actions, and in the end, they might even help him heal some of his emotional wounds. And there could be a lot of action scenes where the reader tries to escape but then realizes that Sasuke is not really a bad guy in this situation.
Well, one plot twist could be that Yassen is actually working for Alex's father all along and the kidnapping is a test for Alex to become a better spy. Another could be that Yassen kidnaps Alex but then realizes Alex has information that could save Yassen's own family, so they form an unexpected alliance. Or perhaps Yassen kidnaps Alex thinking he's someone else, and when he discovers the truth, he has to figure out what to do with this innocent boy in his custody.
Another idea is that the fanfiction could be a dark, alternate universe story where Jasper has turned evil. His reasons for kidnapping Bella could be tied to some sort of revenge plot against the Cullens. He might hold a grudge against them for something that happened in the past, and Bella is just a means to get back at them. This would create a very different dynamic compared to the original Twilight story.
In a Toga kidnaps Midoriya fanfiction, the plot could go in various directions. Maybe Toga kidnaps Midoriya to trade him for something she wants from the heroes, like the release of a fellow villain. Midoriya, on the other hand, could try to escape by using his wits and his knowledge of Toga's weaknesses. For example, if he figures out that she has a soft spot for a certain type of person or situation, he could use that to his advantage. Also, the story could involve the other students at U.A. trying to rescue Midoriya. They might come up with a clever plan that involves using their individual quirks in a unique way to outsmart Toga and get Midoriya back.
One possible plot twist could be that Loki actually has a noble reason for kidnapping Tony. Maybe he wants to use Tony's intelligence to stop a greater threat that the other Avengers are unaware of. For example, there could be a hidden enemy that Loki has knowledge about, and he believes only Tony can help create a device or strategy to defeat it.