Another plot could be that a time - traveling wizard from the future kidnaps them to prevent some future catastrophe that they unknowingly cause. James and Lily then have to figure out how to get back to their own time while also dealing with the kidnapper's motives and the strange future world they find themselves in.
One possible plotline could be that Annabeth is kidnapped by a group of mythical creatures who mistake her for someone else. They take her to their lair deep in the forest. Her friends then have to embark on a dangerous journey to find her, facing various challenges along the way. Another could be that a powerful enemy from her past kidnaps her to use her knowledge of architecture for some evil plan, like finding a hidden powerful artifact.
One possible plotline could be that Osomatsu is kidnapped by a rival gang who wants to use him as a bargaining chip against his brothers. His brothers then have to go on a wild adventure to rescue him, facing various challenges along the way. Another plotline might be that he is kidnapped by a crazy fan who is obsessed with him and wants to keep him all to herself. Osomatsu has to figure out how to escape while dealing with the fan's erratic behavior. And a third plotline could be that he is kidnapped by an evil entity from another dimension who mistakes him for someone with special powers.
In a fanfiction where Carl Grimes is kidnapped, he could be taken by a group of survivors who are desperate for supplies. They see Carl as a valuable asset to trade with his group. Carl, while kidnapped, tries to convince them that working together would be more beneficial. He might share his knowledge of survival skills and how his group has managed to build a community, hoping to change their minds and gain his freedom.
One possible plotline could be that Darcy is kidnapped by a group who want to use her knowledge of a certain scientific discovery she was involved in. They might hold her in an abandoned warehouse and try to force her to reveal the details. Another could be that she's kidnapped by an alien species who mistake her for someone more important in the scientific community on Earth. They take her to their ship and she has to find a way to escape while also learning about their motives.
One possible plotline could be a time - travel scenario. Maybe Ginny somehow travels back in time and meets James and Lily. They could form a bond and Ginny could learn a lot about Harry's early life and family history directly from them.
Well, a plotline might involve them facing challenges from the wizarding world. For example, there could be threats from dark wizards which they have to fight together as a married couple. Or perhaps they get involved in some sort of magical research as a team in their married life. Also, their relationship growth is a big part. They could have little arguments and then make up in the most romantic ways, like James bringing Lily her favorite flowers after a fight.
One possible plotline could be that Lily and James return during the time of Harry's battle with Voldemort. Their return could give Harry new strength and hope. They might use their old magical knowledge and skills to help in the fight. Maybe they could also reunite with their old friends like Sirius and Remus, and together they form a powerful force against the Dark Lord.
Perhaps Drake is kidnapped because he has uncovered a dark secret in Ripper Street. The kidnappers could be trying to silence him. His captors might hold him in an abandoned building, and he has to use his wits to try and escape while his colleagues search the seedy underbelly of the street for him. This could involve a lot of tense moments as the kidnappers threaten him and his friends get closer to finding him.
One possible plotline could be that Hinata is under some sort of mind - control. Maybe an enemy uses a jutsu on her that makes her see Naruto as a threat to the village in a false way. So, she kidnaps Naruto to stop him from doing something she believes is harmful. But as the story progresses, Naruto tries to break through to her real self and free her from the mind - control.
One possible plotline could be that Naruto is kidnapped by Kyuubi to gain some sort of power or knowledge from him. Maybe the Kyuubi believes Naruto has a secret that can help it break free from its current state. Another could be that Naruto is kidnapped as a way to get back at the Hidden Leaf Village, and the Kyuubi uses Naruto as a bargaining chip. It could also be that there is some external force that makes the Kyuubi kidnap Naruto, like a dark wizard or something similar that has control over the Kyuubi.