They could also be developed together by going through a major crisis as a couple. Let's say there's a natural disaster in the town. How they support each other, make sacrifices, and come out stronger on the other side would really deepen their characters and their relationship.
For Aden, he could be developed by showing his growth in dealing with his past traumas. Maybe he starts to open up more about his difficult childhood and how it has affected his relationships, especially with Belle. This would make him more empathetic.
Another idea is a time - travel fanfiction. Aden somehow gets sent back in time to a crucial moment in his and Belle's relationship. He has the chance to change things that went wrong in their past, like a big argument they had that almost ended their relationship.
In fanfiction, Belle's character could be further developed by having her struggle with her own insecurities. Maybe she feels that she's not enough to fully break the curse. Adam, on the other hand, could be developed by showing his internal conflict of wanting to be fully human again but also being afraid of losing the part of him that Belle fell in love with as the beast. Their relationship could grow as they help each other through these internal battles.
Hook's character can be developed through his relationship with Belle. He could start to value things like knowledge and kindness more as he spends time with her. He might even start to read books under her influence! Belle, on the other hand, could become more worldly. Hook could introduce her to the rougher side of life outside of her castle and library, and she could learn to adapt and use that knowledge to help others in different situations.
For Big Mac, he could be developed by showing his more emotional side. Maybe he writes poetry for Sugar Belle in secret. For Sugar Belle, she could be shown taking on more leadership roles in the community, with Big Mac's support. This would show her growth and confidence.
You can develop their relationship further by adding more challenges. For instance, introduce a character who is jealous of their relationship and tries to drive them apart. This could test their love and loyalty to each other. They would then have to fight for their relationship, which would strengthen their bond in the end.
Their relationship could be developed by having them communicate more deeply. For example, Haku could share more about his past and his true form with Chihiro. This would create a stronger bond between them as Chihiro would understand him better.
For Bart, you could explore his softer side more. Show how he really cares about his family deep down, even if he acts out. For Lisa, perhaps show her struggling with non - academic things like making friends outside of her usual intellectual circle.
You could also develop their characters through their relationships with other characters in the fanfiction. If they have friends or foes, how they interact with them can reveal more about who they are. For example, if they have an enemy, do they fight back bravely or try to find a peaceful solution? This can tell us a lot about Reiji and Xiaomu.
Victoria's character can be developed by making her more assertive. In the context of fanfiction with Agent 47, she could start to take on more dangerous tasks and prove herself. For example, instead of always relying on Agent 47 for protection, she could save him in a crucial moment, which would show her growth and independence.
For Hansel, you could show his growth from a scared little boy to a brave young man. Maybe he starts learning self - defense techniques after the encounter with the witch. Gretel could be developed as a more strategic thinker. For example, she could start making maps of the forest and surrounding areas to prevent them from getting lost again.