I'm not really into this kind of 'forced' concept in fanfiction. However, if we analyze it in a general sense, it might be a very dark and unethical take on the relationship between Lucy and the celestial spirits. It goes against the normal friendly or contractual relationships depicted in the original work.
Most likely not. The fan community generally values positive and respectful interpretations of characters and their relationships. A 'forced' relationship as described in this fanfiction goes against those values.
In Fairy Tail celestial spirits fanfiction, writers get creative with the powers and personalities of the spirits. Some may give a spirit a backstory that wasn't explored in the original. For instance, Aquarius could have a past that involves an ancient water civilization, which adds more depth to her character and her relationship with Lucy.
Another good one is 'Celestial Bonds Renewed'. This fanfiction explores the idea of the celestial spirits' bonds with their summoners being tested in new and unexpected ways. It's full of emotional moments between the characters, especially Lucy and her spirits.
One interesting aspect could be how she trains to become a Celestial Dragon Slayer. Maybe she discovers an ancient magic that combines the two, and she has to learn to control the newfound power. This could lead to some great character development as she struggles with the increased power and the responsibility that comes with it.
A fanfiction idea could be that Lucy's Celestial Spirit King Star Dress is coveted by a rival guild. They try to steal it from her during a grand magic tournament. Lucy, along with Natsu and the rest of Fairy Tail, has to protect the dress while also competing in the tournament. This leads to intense battles and strategic maneuvers, and in the end, Lucy realizes the true potential of the star dress not just as a power boost, but as a symbol of her connection to the celestial spirits.
One possible storyline could be Lucy's adventures with her spirits as they face a powerful new enemy together. The spirits might use their unique abilities to protect Lucy.
One idea could be creating an OC celestial spirit that has a unique power related to time. For example, it can freeze time briefly in a small area. Another idea is an OC that has a special bond with a main character from Fairy Tail, like Lucy. Maybe the OC celestial spirit was once a human who was transformed into a spirit due to a powerful magic spell long ago. Also, you could write about an OC celestial spirit who has a conflict with the existing celestial spirit system and tries to change it for the better.