Perhaps the chains are a part of a prophecy. Instead of restraining Lucifer, they are meant to transform him into a different being altogether. This would completely change the direction of the fanfiction and lead to unexpected alliances and conflicts as the other characters deal with this new Lucifer.
A possible plot twist could be that the chains are not as effective as they seem. Lucifer might be faking his inability to break free and is actually using this as a ruse to gain the trust of his captors before making a grand escape.
One aspect could be the character development of Lucifer in this fanfiction. Maybe he is in a chained state which restricts his power, leading to a different dynamic compared to his normal, more powerful self in the original 'Supernatural' series.
Well, perhaps Harry would have a much darker personality. Azkaban's gloomy environment could have made him more cynical. He might start to question the very nature of the wizarding world. And when he finally gets out, he could be on a mission to completely change the way Azkaban is run, or even the whole justice system in the wizarding world. Since he grew up surrounded by the so - called 'criminals', he might realize that not all of them are truly bad.
Sure. A simple plot could be that Draco is chained up by dark wizards who want to use him as a bargaining chip against his family. His friends from Hogwarts then set out on a dangerous mission to rescue him.
Power is a major theme. Two Lucifers would bring a lot of power into one story, and it can be about who has more power or how they use their power together.
It could be a situation where Harry has been wrongly accused. Some overzealous magical law enforcers chain him up and confiscate his glasses as a form of punishment before a proper trial. This would create a lot of internal conflict within Harry, feeling betrayed by the very system he has been fighting for.
A plot idea could be that Lucifer wakes up in a human body with no memory of who he is. He starts living a normal life until strange things start happening around him that hint at his true identity. As he slowly regains fragments of his memory, he has to decide whether to embrace his old self or continue his new life.
A possible plot twist could be that Naruto discovers he has a hidden connection to Smaug. Maybe he is related to Smaug in some long - lost magical way. Another twist could be that Smaug is not really a villain in this fanfiction. Instead, he is being controlled by a greater evil, and Naruto has to figure out how to free Smaug from this control. It would change the whole dynamic of their relationship from one of enmity to a more complex situation where they could potentially become allies.
A great plot twist could be that one of the investigators is actually related to the main villain they've been chasing all along. Maybe they find out halfway through the story. Another twist could be that the evidence they've been gathering was planted by someone else to mislead them. So, they have to start all over again.
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 possible plot twist could be that Naruto turns out to be a keyblade wielder in disguise. This would completely change the dynamic as everyone in the Naruto world and Kairi would be shocked. It could also mean that Naruto has a whole different origin and mission related to the world of Kingdom Hearts.