Their friendship can be developed by having them face a really tough challenge together. For example, if they are trapped in a dangerous magical maze. They would have to rely on each other's strengths. Lucy's intelligence and Aquarius' power could be combined to find a way out. This would deepen their bond.
In a story, their friendship could be further developed if Aquarius starts to open up more about her past and her feelings. Lucy could be there to support her. Maybe Aquarius has some regrets or fears that she shares with Lucy. And in return, Lucy can tell Aquarius more about her dreams and hopes for the future of Fairy Tail. They could also have some light - hearted moments like shopping together in a magical marketplace, just having fun and getting to know each other better on a more personal level.
One way to develop their friendship is through sacrifice. If Lucy has to give up something important to save Aquarius, or vice versa. This would show the depth of their care for each other. Also, they could train together. Aquarius could teach Lucy some unique water - based magic techniques while Lucy could share her knowledge of celestial spirit magic with Aquarius. Through this exchange of knowledge and mutual growth, their friendship would surely grow stronger.
Lucy could give Aquarius more freedom outside of the key. Let her experience the human world more often. They could go on adventures that are not related to Fairy Tail's main quests, just the two of them. This would allow them to get to know each other on a more personal level. Aquarius could also teach Lucy more about celestial magic and its deeper secrets, which would bring them closer as they explore this knowledge together.
For Hibiki, his character could be developed by exploring his relationship with his guild more deeply in the context of his interactions with Lucy. Maybe he has some insecurities about not being as strong as some of the other guild members, and Lucy helps him see his own value through their adventures.
For Lucy, her character could be developed by showing her learning new and advanced celestial magic spells from Yukino. This would not only expand her magical abilities but also show her determination to grow stronger. For Yukino, she could be developed by showing her becoming more confident in making decisions outside of her guild's rules, influenced by Lucy's more independent nature.
Lucy could be developed further by exploring her family background more deeply. Maybe she discovers some long - lost relatives who are also involved in magic. This could add new layers to her character. Another way is to show her struggling with her insecurities about her magic abilities and then gradually overcoming them through various challenges.
For Lucy, you could explore her celestial spirit powers more deeply. Maybe she discovers a new and rare spirit that has a special connection to Rogue or Sting's magic. For Rogue, his relationship with his shadow could be further developed. He might learn to use his shadow in new ways, and Lucy and Sting could play a role in that discovery. For Sting, his leadership skills could be tested and improved. They could be put in a situation where Sting has to lead a group that includes Lucy and Rogue, and he has to make tough decisions.
Lucy could be developed by showing her struggle to control the more powerful star dresses. For example, she might initially be overwhelmed by the strength of a new star dress but gradually learn to master it through training and self - discovery. This would show her growth as a mage.
One way their relationship could develop is through a mutual understanding of their powers. If they start training together to combine their celestial magic in new ways, they'll have to communicate and rely on each other more. This would not only strengthen their magical bond but also their personal relationship. Another aspect could be that they face a situation where they have to make sacrifices for each other. Say, Lucy has to give up a chance at a powerful magical item to save Loke, or Loke has to put himself in great danger to protect Lucy's family. These kinds of selfless acts would take their relationship to a new level.
Lucy can develop her kindness further. For example, when she first meets the cat, she could show great compassion towards it, even if it's a bit of a troublemaker. This would highlight her nurturing side, which is an important part of her character.
Putting Wendy in a leadership role within the guild for a fanfiction story would be interesting. She could learn to be more assertive and make tough decisions, which would help her grow as a character. It would also show how she can inspire others in the guild.
For Freed, his character could be developed by exploring his past more deeply. Maybe there are some secrets about his family or his early days in magic that could be revealed. This would add more layers to his personality. For Rufus, we could see him struggle with the pressure of always having to remember everything perfectly. This internal struggle could change his character over time.