When it comes to how the characters' personalities change in this crossover, it's quite complex. Marinette, as Ladybug, may start to show a more vulnerable side. The beauty and danger of the Swan Lake world make her realize that she can't always be in control. Chat Noir might become more solemn. The grandeur and the dark undertones of Swan Lake could make him more aware of the seriousness of their situation. And for other characters like Chloe, she could either be completely out of her depth and become more submissive or, in a twist, she could try to take on the role of a villain within the Swan Lake story, using her mean - girl tactics in a different, more magical context.
Marinette might become more confident if she's reborn. In the original, she's often shy and clumsy, but in a reborn scenario, she could use her past experiences to be more assertive. For example, she might not stutter as much around Adrien. Adrien, on the other hand, could become more carefree if reborn. He's usually burdened by his family life, but a new start could make him more open to having fun. Chat Noir might also show a different side, perhaps being more strategic instead of just going in head - first all the time.
In the werewolf form, Chat Noir might become more aggressive. His usually flirty and carefree nature could turn into a more territorial and protective one. He would be more likely to attack threats without hesitation. For Ladybug, she could become more instinct - driven. Her normally calm and collected self might struggle to keep her emotions in check, as the werewolf form brings out more primal instincts. And for characters like Alya, she might be more curious and fearless in werewolf form, always eager to explore and learn about this new side of herself.
Anna, being outgoing and adventurous, would probably get along great with Chat Noir. They could have a lot of fun banter and adventures together. When it comes to Elsa and Hawk Moth, Elsa's coldness (in personality as well as power) would be a contrast to Hawk Moth's manipulative and power - hungry nature. She would be very resistant to his attempts to use her for his evil plans.
If the kwami swap involves a kwami with a mischievous nature, Lady Noir's personality could become more playful. She might start cracking more jokes during battles, much like Chat Noir usually does. This would change her overall demeanor and how she interacts with both the villains and Chat Noir. It could also make their partnership more light - hearted or, if Chat Noir isn't used to it, a bit more chaotic as they adjust to this new side of Lady Noir.
The relationship between Ladybug and Chat Noir might become more strained as they might have different ideas on how to prevent something like the Collector incident from happening again. On the other hand, Marinette and Alya's friendship could grow stronger as Alya supports Marinette through the aftermath. And Adrien might become more distant from his father as he realizes the importance of his role as Chat Noir and the potential danger his father's actions (if related to the Collector in some way) could pose.
For Chat Noir, if he's the one sleeping in the fanfiction, we could see how Ladybug reacts to his vulnerable state. This can show her caring side. And Chat Noir's dreams could also be used to explore his past or his desires. If he dreams of a world without Hawk Moth and he can be with Ladybug freely, it shows his longing for a normal life and his love for Ladybug. The way he behaves in his sleep, like murmuring Ladybug's name, can also give insights into his passionate and somewhat impulsive personality.
One interesting plot twist could be that instead of Hawk Moth being the main villain, it's someone from the Swan Lake story who has been corrupted by dark magic. For example, Rothbart could be working with Hawk Moth to create more chaos. Another twist might be that Ladybug and Chat Noir get trapped in the world of Swan Lake and have to find a way to break the curse there in order to return to Paris and continue fighting akumas.
Marinette is shy and often nervous, while Alya is bold and outgoing. Their personalities can create a great dynamic. Alya can encourage Marinette to be more confident and take risks. For example, when Marinette is hesitant to enter a fashion competition, Alya pushes her to do it.
Well, if Marinette was a witch, her relationship with Adrien might be more complex. She could be hesitant to get close to him because of the secrets her witch heritage holds. And Adrien, if he had some sort of angelic nature, might initially be a bit aloof towards Marinette as he tries to keep his true self hidden. Their relationship as Ladybug and Chat Noir would also be different. They might have a deeper, more spiritual connection through their Miraculous.
The akuma might transform Ladybug's outfit into something dark and sinister, or it could turn it into a costume inspired by a different theme altogether.