Another plot twist might be that the kidnapping was a misdirect. It could be that the kidnapper actually intended to target Sherlock all along and thought using Joan as bait would be the best way to draw him out. So, they set up this elaborate kidnapping scenario for her.
One possible plot twist could be that Joan's kidnapper turns out to be someone she knew in the past, like an old acquaintance with a grudge. Maybe it was someone from her college days who felt she had wronged them in some way.
Perhaps a really unexpected plot twist could be that Joan is not actually kidnapped in the traditional sense. Instead, she is being held in a place that she herself had some connection to in the past. Maybe a place she had visited during a case and unknowingly left some sort of loose end that has now come back to 'kidnap' her in a way.
It could be a criminal that Sherlock and Joan put away. This person might have escaped from prison or had an accomplice on the outside who planned the kidnapping as revenge. For example, a mastermind criminal who lost a lot because of their capture.
A really unexpected plot twist in this kind of fanfiction might be that the kidnapping was a mistake. The kidnapper was actually after someone else but got the wrong duck. This could lead to all sorts of comical or tense situations as they try to figure out what to do with the wrong captive. Also, the kidnapped character could discover a long - lost secret about their family during their captivity, which changes the whole dynamic of the story.
A great plot twist would be if Raven is kidnapped and taken to a place where she meets her long - lost family members, but they're the ones who kidnapped her because they need her help to fight against a common enemy, and they knew this was the only way to get her attention. Another plot twist could be that the kidnapper has a split personality, and one side is good and wants to free Raven, while the other side is evil and wants to keep her captive. And the last plot twist might be that Raven is kidnapped into a parallel universe where everything is different, and she has to find a way back while also dealing with the kidnapper in this strange new world.
One possible plot twist could be that the kidnappers were actually working for a powerful dark wizard who wanted to use Hermione's intelligence for his own evil plans. Maybe they planned to brainwash her into becoming a powerful weapon against the wizarding world. Another twist could be that Hermione's real family had a dark secret and the kidnapping was an attempt to keep her away from it. For example, her family might have been involved in some sort of ancient dark magic that they didn't want her to discover. Or perhaps the kidnappers thought they were rescuing her from a prophecy that would bring doom to her if she stayed with her birth family.
Maybe the kidnappers are actually part of a rival music group. They kidnap Austin and Ally to stop them from performing at a big event, which would give their own group a better chance to shine. They hold them hostage until the event is over.
Well, perhaps the kidnapping is a fake - out. Barry is actually working with the 'kidnappers' to infiltrate a criminal organization. He pretends to be kidnapped so he can get inside and gather information. This would add an interesting layer of deception to the story and could lead to some really exciting moments when the other characters start to figure out what's really going on.
One possible plot twist could be that the kidnapper is actually someone Nicole knew in the past, like an old acquaintance with a grudge. Maybe it was someone from her school days who had a secret crush on her and when she rejected them, they held onto that anger and now are seeking revenge.
A big plot twist could be that Artemis was actually faking his kidnapping as part of a bigger plan to infiltrate an enemy group. He lets himself be taken so he can gather intel from the inside.
A plot twist might be that Shawn was actually expecting to be kidnapped. He could have been working undercover on a case and let the kidnapper take him on purpose to get closer to the real bad guys. It could also turn out that the kidnapper is a deranged fan of Shawn's detective work. They kidnapped him not to harm him but to force him to solve a mystery that only they believe in. And there's the chance that the whole kidnapping is an elaborate illusion created by Shawn himself as part of a bigger plan to expose a criminal organization that has been one step ahead of the police for a long time.
One possible plot twist could be that Draco actually has noble intentions behind the kidnapping. Maybe he's trying to protect Hermione from a greater threat that she's unaware of. For example, there could be a dark wizard targeting her specifically, and Draco, despite his past enmity, decides to take matters into his own hands to keep her safe.