Apollo could marry Artemis' handmaiden. Since he often crosses paths with Artemis and her group, he might fall for one of the gentle and nature - loving handmaidens. This would be an interesting choice as it would also create a connection between Apollo and Artemis in a new way.
One possible plot could be that Apollo marries a mortal. He might meet her in a beautiful garden where she is tending to the flowers. He is immediately smitten by her beauty and kindness. Their relationship could face many challenges, like the wrath of other gods who think Apollo is making a mistake by choosing a mortal. But Apollo's love for her is so strong that he is willing to face any consequences to be with her.
Her spouse could be a nature spirit. Since Artemis is closely associated with nature, a nature spirit would be a fitting partner. They could understand her love for the forest and all living things.
The plot could start with Apollo being intrigued by Harry's unique magic. They start spending time together and realize they have a lot in common. They get married in a grand ceremony that combines both wizarding and divine traditions. As a married couple, they travel between different dimensions, helping those in need. Along the way, they have to deal with internal struggles, like Harry's insecurities about being with a god, and external threats, such as dark forces that want to break them apart.
Yes, there are some out there. You can start by looking on popular fanfiction websites like Archive of Our Own. Some might explore unique concepts of their relationship, like how their different magical or divine powers interact within the context of a marriage.
A mortal poet or singer could be a likely love interest. Apollo is the god of music and poetry, so he might be drawn to someone with a great talent in those areas. Another could be a beautiful nymph. Nymphs are often associated with nature and beauty, which would attract Apollo. Or perhaps a priestess dedicated to his worship. She would already have a spiritual connection to him, which could easily turn into a romantic one.
It could be a dark figure from Greek mythology who wants to stop Naruto from fulfilling Apollo's will. Maybe a Titan who is jealous of Naruto's new - found connection to Apollo.
It could be Hades. He might not like the idea of Percy, a son of Poseidon, being friends with Apollo. Hades could see it as a threat to his own power or plans in the underworld.
Some fanfictions might also take a more creative approach. They could place Apollo in alternate universes, such as a world where the legal system is completely different. In this setting, Apollo Clay has to adapt to new rules and challenges, which makes for an exciting read as we see how his core values as a lawyer are tested in these strange new scenarios.
Well, it could be about Naruto somehow being connected to Apollo's powers. Maybe he gains some of Apollo's abilities like archery skills or the power to heal. It could also be a story where Naruto is a reincarnation of Apollo in the Naruto universe.
Love against all odds is also a prevalent theme. Apollo's status as a god might bring many obstacles to his marriage. But in fanfic, love often conquers all. There could be stories where he has to fight other gods or face the wrath of Zeus to protect his marriage. This shows the power of love in the face of great challenges.