Another idea is that Percy discovers he has a long - lost vampire heritage. As he becomes a vampire, he starts to unlock memories and powers related to his vampire lineage. He could go on a journey to find out more about his vampire ancestors and the secrets they held, all while adjusting to his new vampiric existence which is full of both challenges and newfound abilities.
His character would likely become more solitary at first. Vampires are often associated with a certain aloofness, and Percy might find it hard to relate to his old friends in the same way. For instance, he may start to avoid social gatherings during the day because of his new sensitivity to sunlight.
If Percy becomes a vampire, his relationships would change drastically. His friends from Camp Half - Blood might be afraid of him or try to find a way to 'cure' him. His relationship with Annabeth would be put to the test. She might be determined to save him, but also conflicted because of what he has become. And Percy himself would have to deal with the fact that he now belongs to a different 'species' so to speak.
There could be an old gardener who mentors Percy. The gardener might teach Percy all about the plants in the garden, their needs, and how to keep the garden thriving.
Obviously, Bella is a main character as the title implies she is the one becoming a vampire. The Cullen family members are also likely to be main characters. Edward, who was in a relationship with Bella when she was human, will surely play an important role. Also, Carlisle, the patriarch of the Cullen family, might be involved in guiding Bella through her new vampire existence.
Maybe Alvin gets bitten by a vampire one night while walking alone. Then he starts to experience the changes like craving blood and having enhanced senses. He could struggle to come to terms with his new identity as a vampire.
In this fanfic, Percy might be seen as an outcast at first among the Avengers because he's so different. But as time goes on, they come to respect his abilities. The story could also explore how Percy's presence affects the dynamics within the Avengers. Does he create new rivalries or alliances? And how does he adapt to their high - tech world when he's used to the more ancient and magical world of the Greek gods? Maybe he even tries to introduce some of his own magic into their technology, leading to some interesting and unexpected results.
Perhaps Percy is pushed to his limits by some great injustice in the story world. Maybe he witnesses the death of someone he loves at the hands of an evil force. This trauma could transform his personality, leading him to become a killer with a vendetta. He might start by targeting the ones directly responsible and then expand his scope as his thirst for vengeance grows.
Well, perhaps Percy discovers some ancient power within himself that gradually transforms him into a god. He might have to face a series of trials to fully ascend, like battling powerful monsters or making difficult moral choices.
Maybe Percy discovers a hidden garden and becomes obsessed with it. He starts to learn about different plants, takes care of them, and the garden becomes his special place.