In a fanfiction, it could be that Reid is kidnapped by a cult. The cult believes that his unique mind can help them unlock some sort of spiritual or otherworldly knowledge. They keep him in a secret location, surrounded by strange symbols and rituals. As the story progresses, Reid has to use his profiling skills not only to escape but also to understand the motives and inner workings of this cult.
One possible plot twist could be that the kidnapper is someone from Reid's past that he thought was long gone. Maybe an old unsub who escaped prison and is seeking revenge. Another could be that Reid is kidnapped as a means to get to the BAU team, and the kidnapper is using him as bait to draw out the whole team for a bigger attack.
It could be a copycat unsub who idolizes the previous criminals the BAU has caught. He might have studied Reid's work and decided to target him to make a name for himself in the criminal world.
Maybe it's a cult leader. The cult might believe that Reid has some sort of special knowledge or power that they want to harness. They kidnap him to convert him to their beliefs or use his mind for their own strange purposes.
One possible plot twist could be that the kidnapper is actually an ally in disguise, trying to protect Mario from a greater threat. For example, they might be taking him away from Bowser's clutches in a way that seems like a kidnapping but is really a rescue mission.
One plot twist could be that the kidnappers turn out to be working for someone Juvia thought was a friend. Another could be that Juvia has a hidden power that she discovers while being held captive, which helps her escape. Or perhaps the person who seems to be the main kidnapper is actually being blackmailed into doing it.
Well, a great plot twist might be that Ponyboy discovers the kidnappers are actually part of a secret society that has been observing him for a special reason. Maybe they think he has some hidden power or knowledge. Also, it could be that during the kidnapping, Ponyboy finds out that there is a traitor among his own group who helped the kidnappers. This would add a whole new layer of drama and mystery to the fanfiction.
One common plot element is Reid using his vast knowledge to try and escape. He might analyze the behavior of his kidnapper, looking for patterns or weaknesses. Another is the emotional turmoil of the BAU team, especially his close friends like Garcia and Morgan.
Well, perhaps Reid secretly married someone who has a mysterious past. He's afraid of how his friends and colleagues will react, especially since they might be investigating something related to his spouse's past without knowing. As the story progresses, he has to balance his work, his loyalty to his team, and his love for his secret spouse. This could lead to a lot of internal conflict for Reid and some tense moments with the team when they start to suspect something.
One popular Spencer Reid kidnapped fanfiction is 'The Abduction of Reid' which focuses on the team's desperate search for him. It has a lot of suspense and great character development.
Well, perhaps in the fanfiction, Reid is kidnapped as part of a plan to blackmail the BAU. The kidnappers demand that the team stop investigating a certain case or they'll harm Reid. It could also be that Reid is kidnapped by a group who believe he has information about a secret government project. Reid then has to figure out how to convince them he doesn't while also finding a way to get free.
A great plot could be that Spencer Reid meets a woman who is an artist. She is very different from him in terms of her creative and free - spirited nature. He is initially intrigued by her unique perspective on life. They start to spend time together, with Spencer learning about art from her and she learning about his academic interests. Their love story could be about how two very different people find common ground and fall in love.