The OC, as the Son of Sparda, could fit in by being a new and powerful entity. He might be initially seen as an outsider, but his powers would quickly draw attention. He could become involved in the power struggles between the different factions in Highschool DxD. For example, the devils might try to recruit him, while the angels might be wary of his presence. His unique abilities would also make him a valuable ally or a fearsome opponent. And in the high school setting, he could be a bit of an enigma to the other students, both human and supernatural.
One great fanfiction could be where the OC has a unique power that Akeno is initially intrigued by. For example, the OC might have the ability to control light in a different way than the devils in the Highschool DxD universe. This could lead to a series of adventures where Akeno and the OC team up to face various challenges. They could start off as just acquaintances but gradually develop a deeper bond as they fight side by side.
One possible aspect could be the unique abilities that Eve might possess in her reincarnated form. In Highschool DxD fanfiction, new characters often bring fresh powers. For example, Eve could have a special power related to light or healing, which would make her a valuable asset to the group. This could also lead to interesting storylines where she has to learn to control her powers while also dealing with the typical Highschool DxD chaos of devils, angels, and fallen angels.
To write a Highschool DxD OC Angel fanfiction, start with a strong concept for your angel. Are they a high - ranking angel with a lot of power or a newbie just learning the ropes? Next, think about their relationships. Who will they be friends with? Enemies? You can also add some unique abilities to your OC, like the ability to heal any wound or the power to manipulate light in a special way. As you write, keep the tone and style of the original series in mind to make it feel like it belongs in the Highschool DxD world.
One great Highschool DxD OC Angel fanfiction is 'The Angel's Ascent'. It has an interesting plot where the OC angel has to navigate the complex world of the DxD universe while hiding her true powers. It's full of action and some great character development.
To write a Highschool DxD OC Peerage Fanfiction, start with a strong concept for your OC. Are they a reincarnated hero? A new type of devil? Once you have that, build the peerage around them. Each member should have their own distinct personality and role. For the plot, you can draw inspiration from the original series like the Rating Games. But also add your own twists. For example, what if there was a new type of Rating Game that only OC peerages could participate in? Write detailed descriptions of the battles, the character's growth, and the evolving relationships within the peerage.
Maybe the OC is a descendant of an ancient race that was once closely associated with the power of Divine Dividing. They come to the high school to find out more about their heritage and end up getting involved in the power struggles between the different factions in the DxD world. This could involve making alliances and enemies along the way.
I haven't read this particular fanfiction yet, but generally, a fanfiction about the son of Sirzechs in the Highschool DxD universe could be really interesting. It might explore new powers, relationships, and storylines that the original series didn't cover. For example, how the OC would interact with the existing characters like Issei and Rias, and how his heritage as the son of Sirzechs would shape his destiny in the Devil society.
There's also 'Phoenix's Redemption'. In this fanfiction, the OC phoenix character has a troubled past and is trying to find their place in the world of Highschool DxD. It has some great character development and action scenes.
First, you need to create a well - developed OC nekomata character. Decide on her appearance, personality traits, and backstory. For example, you could make her a shy nekomata who was raised in a hidden nekomata village. Then, think about how she will interact with the existing characters in the Highschool DxD universe. Will she be friends with Issei? Or maybe she has a rivalry with a certain devil.