Esdeath's character can be developed by exploring her backstory in relation to the thief. Maybe she had a similar experience in her past where she was an outcast like the thief. This can make her more empathetic towards the thief. The thief's character can be developed by showing their growth from being a simple thief to someone who has a greater purpose, perhaps influenced by Esdeath's grand plans. As they interact, both characters can change and adapt, making their relationship more complex and interesting.
One plot idea could be that the thief is initially stealing from Esdeath's domain. Esdeath catches the thief but is intrigued by their skills and instead of punishing them, forces the thief to work for her. As they spend time together, an unlikely bond forms between the cold - hearted Esdeath and the wily thief.
Tatsumi is very likely to be involved as he has a significant relationship with Esdeath in the original story. Her subordinates in the Jaegers might also be part of the fanfic. They could be shown as being protective or having mixed feelings about her pregnancy.
To develop Ahsoka's character, show her struggle with her identity outside of the Jedi Order when she's with Padme. Maybe she's trying to find a new purpose. Padme can be the one to encourage her to use her skills in different ways. For Padme, show her more vulnerable side. When she's with Ahsoka, she can let down her political facade a bit. They can have heart - to - heart conversations that allow the reader to see deeper into their characters.
For Smoker, you can show his growth in terms of his leadership skills. Maybe at the start of the fanfic, he is a bit too head - strong. But as he works with Hina, he learns to be more diplomatic. For Hina, her character can be developed by showing her softer side. Usually she is seen as strict, but in the fanfic, she could show kindness towards Smoker which is a new side of her.
For Bunnicula, you can develop his character by exploring his backstory. Maybe he was once a normal rabbit but was turned into what he is now. This could add depth to his character. As for Chester, show his relationship with the other pets in the house in more detail. Have him interact with them in different ways. In the story, let Bunnicula teach Chester about his world, which will make Chester more understanding and less paranoid. Also, give them both goals. Bunnicula might want to find a way to be more accepted in the household, and Chester could aim to be a better protector.
Luma's character can be developed by highlighting its curiosity. It's new to the universe in a sense, so it can constantly be asking questions, exploring new things. You can also show its loyalty to Rosalina, like how it always stays close to her and follows her instructions without hesitation. As the story progresses, Luma could grow in confidence, starting from a bit of a timid character to one that can face challenges on its own, with Rosalina's teachings in mind.
For Fiora, you can focus on her noble upbringing and her sense of honor. Show how these traits influence her actions when she meets Aatrox. For example, she might be disgusted by Aatrox's use of dark magic but also respect his power.
For Aatrox, you could focus on his past as a Darkin. His internal struggle between his dark nature and any glimmers of his former self could be explored. Show how Fiora's presence either exacerbates or soothes this conflict. For Fiora, her pride as a duelist is key. You can show how she reacts when faced with Aatrox's power that might be greater than what she's used to. Does she become more determined or is she momentarily daunted?
For Apollo, you can emphasize his confident and sometimes over - confident nature. Show his love for music through his actions, like constantly humming a tune or being drawn to any musical event. For Britomartis, highlight her connection to nature, perhaps she's always surrounded by gentle animals or has the ability to make plants grow with a touch.
For Dimentio, show his internal conflict. He might be torn between his loyalty to a certain group and his newfound friendship with Mimi. As for Mimi, make her grow. Let her be more than just a one - dimensional character. For example, she could start as a bit of a spoiled character but through her experiences with Dimentio, become more selfless and brave.