Perhaps Percy kidnaps Annabeth because he has been misinformed about her. He might believe she has done something terrible, like betrayed the demigods or the gods themselves. As the story unfolds, he discovers the truth, that she has been framed, and then they have to work together to clear her name and stop the real wrongdoers.
Well, perhaps a plot twist could be that Percy's friends think he's been kidnapped by someone else entirely. So they're looking in all the wrong places while Khione has him hidden away. Or, it could be that Khione kidnaps Percy but then realizes she's made a huge mistake because Percy has some sort of connection to a force that can destroy her. So she has to figure out a way to either let him go or use him to her advantage in a different way. Also, what if Percy is able to communicate with the elements in Khione's domain and he uses that to his advantage to escape or gain the upper hand?
At first, their relationship would be extremely tense. Annabeth would be angry and confused about Percy's actions. However, as time passes and they start to communicate, they might begin to understand each other's motives better. If Percy had a good reason for the kidnapping, like protecting her from an unseen danger, Annabeth could start to see him in a different light.
One possible plot twist could be the discovery of some hidden power in their unborn child. In the world of Percy Jackson, powers are often unexpected. Maybe the baby has a unique ability related to both Annabeth's wisdom and Percy's water - controlling powers. This could lead to various adventures as they try to protect the baby from those who might want to use its power for evil.
The story could develop in many ways. If it's a more angsty fanfiction, Annabeth might feel betrayed by Percy and their relationship would be severely strained. They would have a lot of emotional turmoil to work through. Meanwhile, the outside world would be in chaos. The gods might get involved, seeing as two of their powerful demigod children are in a strange situation. Percy would have to find a way to make things right, either by undoing what he did or by justifying his actions in some way.
One popular 'annabeth kidnaps percy fanfiction' might be 'The Unplanned Abduction' where Annabeth has some rather complex motives for taking Percy. It delves into her character's insecurities and how she believes kidnapping Percy could solve some of the problems in their world. However, this is just one example and there are likely many others out there.
Well, perhaps they sneak out to meet a mysterious figure who claims to have information about Percy's father, Poseidon. But when they get there, it turns out to be a trap set by one of their enemies. They then have to use their wits and powers to escape and figure out who is behind it all.
One interesting plot twist could be that just before the engagement, Percy discovers he has some long - lost family secret that might put Annabeth in danger. So he has to decide whether to go through with the engagement or keep her safe first. Another could be that an old enemy resurfaces and tries to stop the engagement by framing Percy for something he didn't do. Annabeth then has to prove his innocence.
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.
Well, in a Dracula kidnaps Mina fanfiction, it could go like this. Mina's friends might think she's dead at first. But then they start to notice strange things around town, like an increase in bat activity. They realize Dracula has taken her. Meanwhile, Mina could be trying to outwit Dracula by pretending to be on his side. She could slowly gain his trust and then find a way to escape when he least expects it.
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.