Lucy's new power would bring a shift in her relationships. With Happy, he might be constantly curious about her Celestial Dragon Slayer magic and pester her with questions. The guild as a whole would view her in a new light. Some might be jealous of her newfound power, while others, like Levy, would be excited to research more about it. This could lead to new friendships forming as Lucy shares her experiences with others in Fairy Tail, and also cause some minor frictions as she has to navigate through the different reactions to her power.
Her relationship with Natsu would likely change significantly. Since Natsu is a dragon slayer, they might become rivals in a friendly way, constantly trying to outdo each other in terms of dragon slaying skills. But they could also team up more often, combining their unique abilities to face greater threats.
In terms of her relationship with Gray, there could be a new dynamic. If'si' reincarnated as Lucy, she might be more competitive with Gray, which could lead to some interesting interactions. Her relationship with the celestial spirits would also change. She could become more like a mentor to them, teaching them new things from her past life or experiences. Also, her relationships with other guild members would likely expand. She might form closer bonds with some of the more reserved members of Fairy Tail, bringing them out of their shells.
Erza might see it as a sign of Lucy growing up and becoming more independent. She could view it as a mark of Lucy's determination and might even be a bit envious of Lucy's newfound self - expression. This could lead to some interesting conversations between them about self - identity and how they each represent Fairy Tail.
Well, if we consider Lucy as a Dragon Slayer in fanfiction, her magic could be really different from the traditional ones. Maybe she'd have a connection to a celestial dragon, which would be so cool. It would combine her existing celestial spirit magic with the new dragon slayer powers. She could use the stars as a source of power, similar to how other dragon slayers use elements, and it would be a fresh take on her character.
Her relationship with other celestial spirit users could be affected. They might be jealous of her new power, or they could see her as a symbol of hope for all celestial spirit magic. If there are any anti - celestial spirit groups in the fanfiction world, they would likely target Lucy more. This would put a strain on her relationships as she has to deal with the added danger. On the other hand, it could also bring her closer to some of the more powerful and reclusive celestial spirit users who are interested in the Aquarius power and what it means for the future of their magic.
It could lead to some really exciting plot twists. Lucy having dragon slayer powers might give her new abilities and challenges that weren't there before.
Well, a plot could revolve around Lucy being the only one who can stop an ancient Celestial Dragon that has been awakened from its slumber and is causing chaos. As a Celestial Dragon Slayer, she has to figure out how to communicate with the dragon first and then find a way to either calm it or defeat it. This could lead to her delving deeper into the lore of Celestial Dragons and her own family's connection to them.
Natsu would probably be very confused and sad at first. He's used to having Lucy around, and her sudden departure would leave a big hole in his daily adventures. He might try to convince her to come back immediately.
Well, she could start off being an outcast in Fairy Tail because her ice powers seem so different from the rest. But then she proves her worth by using her ice dragon slayer magic to save the guild from a powerful water - based enemy. The ice would counter the water and she'd become a hero.
Lucy as an Ice Dragon Slayer could have a very different story arc. Her magic could attract the attention of dark guilds who want to use her power for their own evil purposes. She would then have to fight not only to protect herself but also the people she loves in Fairy Tail. Her training to become a stronger ice dragon slayer would involve learning how to control the cold and use it in combat in the most effective ways.