To develop the characters in a Rex x Breach fanfic, consider their individual goals. Rex might have a goal of making the team the best it can be, and Breach could have a goal of proving himself. As they interact, these goals can either clash or merge. For instance, Breach's need to prove himself could initially cause problems for Rex's team - building efforts. But as they work through it, they both grow. Rex learns to be more patient and understanding, while Breach learns the importance of the team as a whole.
In a Rex x Breach fanfic, Rex could be developed by exploring his past traumas and how Breach helps him heal. Breach, on the other hand, can be developed by showing his growth in terms of his loyalty. He starts off as a bit of a loose cannon, but as he spends more time with Rex, his loyalty to the team and especially to Rex deepens. This can be shown through his actions in difficult situations, like when the team is in danger and he puts himself at risk to protect Rex.
For Rex, you could develop his character by showing his more vulnerable side when he's around Breach. Maybe he's usually the tough leader, but with Breach, he allows himself to show his doubts and fears. For Breach, show how he matures through his interactions with Rex. For example, he could become more responsible.
Their relationship can be developed through shared adventures. For example, going on quests where they rely on each other's skills. Rex might need Mythra's combat abilities and Mythra could need Rex's determination and kindness.
Maybe a fanfic where Rex discovers a hidden talent of Breach that no one else knew about. For example, Breach is an amazing artist but has been hiding it. Rex encourages Breach to show it to the world, and through this process, their relationship blossoms. It could also involve some challenges from the other members who don't believe in Breach's new - found confidence.
For Ahsoka, her character could be developed further by exploring her feelings of being an ex - Jedi. She could struggle with her place in the galaxy now that she's no longer part of the Jedi Order. Rex, on the other hand, could be developed by showing his life after the Clone Wars. Maybe he has a hard time adjusting to a new way of life without the structure of the military.
Pacman could be developed by showing his vulnerability. Usually seen as a strong and fast dot - eater, in the fanfic, he could be in situations where he's not so confident. For example, when facing a new kind of threat in Pinky's world. Pinky, on the other hand, could be developed by showing her kindness. We usually see her as a chaser, but here she could be shown as a protector, protecting Pacman from other threats in the game world.
They can be developed through facing challenges. For example, if they encounter a difficult puzzle or enemy, they have to use their wits and skills. This shows their growth.
For Snivy, you can show its growth from being a bit naive to more confident. For example, at the start, it might be hesitant in battles, but as the story progresses, it becomes bolder. Servine can be developed as a more mysterious character at first, with its past gradually being revealed as it gets closer to Snivy.
For Error, you could develop his character by showing his softer side when he's around Ink. Maybe he starts to care more about the things Ink creates instead of just wanting to destroy them. As for Ink, he could become more understanding of Error's glitches and not just see him as a nuisance. The lemon could be a factor in this development. For example, if the lemon has some sort of calming effect on Error, Ink could use that to his advantage to get closer to Error.
For Rukia, her character could be developed by showing her learning new skills or techniques from Sode no Shirayuki. This would not only make her stronger physically but also show her growth in terms of her adaptability. For Sode no Shirayuki, we could see her develop more of an emotional side as she spends time with Rukia. Maybe she starts to understand human emotions better.
To develop Divine, you could start by exploring their backstory. Maybe they come from a long line of magic - users but have a unique power that sets them apart. This could lead to internal struggles as they try to master this power. For Legeater, perhaps focus on their physical abilities and how they got them. Were they trained by a master? Or did they develop them through self - discipline?
To develop the characters in a 'naegi x harem fanfic', consider their backstories. If one of the female characters had a difficult past, it can shape how she approaches Naegi and the other harem members. Also, let their relationships with Naegi evolve over time. Maybe at first they're just friends, but as they face challenges together, their feelings change. You can also use dialogue to show their growth. For example, a character who was initially quiet starts to speak up more as she becomes more confident in her relationship with Naegi.