Perhaps the kidnapping is part of a larger plot by an enemy of both the Winter Soldier and Darcy's friends. The Winter Soldier might be used as a tool, and Darcy could end up being the key to breaking his brainwashing. She could start to form an unexpected connection with him during her captivity, leading to a change in both of their fates.
In some fanfictions, the initial kidnapping could be a mis - understanding. The Winter Soldier might think Darcy is someone else who is a threat. As he holds her captive, he discovers she is an innocent. Meanwhile, Darcy's friends are on a mission to rescue her, which could lead to a big showdown. During this time, the Winter Soldier and Darcy might develop a strange bond that challenges his loyalty to his captors and her perception of him as a villain.
Well, I'm not sure of specific 'Winter Soldier kidnaps Darcy' fanfiction titles off the top of my head. But you can also try FanFiction.net. Sometimes fan communities on social media platforms like Tumblr might also discuss or recommend such stories. They could be a good source to find what you're looking for.
One possible plot could be that the Winter Soldier is under some mind control still and is made to believe Tony is a threat to a certain organization. So, he kidnaps Tony to bring him to his handlers. But during the journey, some of the Winter Soldier's old memories start to surface, which makes him question his mission.
Well, in this type of fanfiction, there are numerous possible plot developments. For example, Mabel might discover some hidden power within herself while being kidnapped by Bill. This power could be the key to her escape or to ultimately defeating Bill. Or, Bill could be using Mabel to access a different dimension or unlock some ancient mystery in Gravity Falls. And the Pines family, along with their allies, would then have to race against time to save Mabel and prevent whatever Bill's evil plan is. There could also be a lot of psychological warfare between Bill and Mabel, with Bill trying to break her spirit and Mabel remaining strong and defiant.
In the 'Lockhart Kidnaps Harry Fanfiction', it could be that Lockhart is being controlled by a dark force without his knowledge. This dark force wants Harry for some evil purpose, like using his connection to Voldemort to resurrect the Dark Lord. Lockhart, being the vain and easily manipulated character he is, is just a tool in this scheme. He might initially think he's in control, but as the story progresses, he realizes he's in way over his head.
One possible plot development could be Sherlock using his brilliant deductive skills to outwit Moriarty even while being kidnapped. He might leave behind subtle clues for Watson to find him. For example, he could use Morse code by tapping on the walls if his hands are tied. Another development could be Moriarty trying to break Sherlock's spirit by taunting him with past failures or the safety of his loved ones. Maybe Moriarty has a grand scheme that involves Sherlock in some way, like using him as a hostage to gain access to certain confidential information from the British government.
Perhaps in the fanfiction, Esmeralda discovers a secret passage in the place where she's held captive by Frollo. She could use this to escape, but then has to evade Frollo's guards in the maze - like corridors. Also, there could be a plot where Frollo has some sort of internal struggle. Maybe a part of him starts to feel guilty about the kidnapping and debates whether to let her go.
One possible plot development could be that Leia uses her wits to try and outsmart Vader during her captivity. She might attempt to manipulate the situation to her advantage, perhaps by feigning cooperation while secretly planning an escape. Another development could be that Luke and the Rebel Alliance launch a rescue mission. They would face numerous challenges, like penetrating Vader's stronghold and evading his forces. And Vader himself might be conflicted about his actions, given his relationship with Luke and the knowledge that Leia is his daughter, which could lead to some internal struggle within him.
One possible plot development could be that Aang and the gang set out on a rescue mission. They might face various obstacles along the way, like dealing with Jet's group's hiding places. Another could be that Katara, while kidnapped, tries to reason with Jet, appealing to his better nature if he still has any left. Maybe she manages to convince some of his followers to turn against him.
In a non - adult 'Sasuke kidnaps Naruto' fanfiction, a possible plot development could be that Sasuke kidnaps Naruto in order to protect him from a greater threat that he doesn't think Naruto is aware of. Maybe there's a new enemy in the Naruto - verse that Sasuke believes only he can handle, and he thinks Naruto will be safer away from the action at first.
A possible plot for a 'Hydra Kidnaps Darcy' fanfiction could involve Darcy's sassy attitude getting on the nerves of her Hydra captors. This could lead to some humorous exchanges while still maintaining the tension of the situation. Meanwhile, the Avengers are frantically searching for her. Captain America might use his leadership skills to coordinate the search efforts. Back with Darcy, she could try to form an alliance with other captives in the Hydra base. Together, they could come up with a plan to revolt against their captors and escape before the Avengers arrive.