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.
Definitely Jinwoo. He has all these cool powers like summoning shadow soldiers and has reached high levels in his leveling journey. Goto doesn't have such powerful capabilities as Jinwoo.
Jinwoo is much more powerful than Goto. Jinwoo has his unique leveling system which has made him extremely strong. Goto, on the other hand, doesn't have such extraordinary abilities compared to Jinwoo. So, in their encounters, Jinwoo would likely be the dominant one.
In this fanfiction, a key element is the conflict that the Son of Sparda OC might face. He's in a new world, Highschool DxD, which has its own set of rules and power dynamics. He may struggle to fit in or be accepted by the different groups. His powers, which are likely a blend of Sparda - like abilities and those related to the devils in Highschool DxD, could make him a target. For instance, some devils might see him as a threat to their power structure. Also, his journey of self - discovery is important. As he learns more about his heritage as the Son of Sparda, he has to figure out how to use his powers and where he stands in this new and complex world.
Well, it could start with the discovery of the OC's identity as Grayfia's son. This would surely stir up a lot of reactions among the different factions in the Highschool DxD universe. He could be thrust into various adventures, like having to protect a certain character or retrieving a powerful artifact. His relationship with his mother, Grayfia, would also play a significant role, perhaps she has certain expectations of him that he struggles to meet while also dealing with his own desires and goals.
One interesting concept could be the unique powers that the son of Trihexa might possess. Given Trihexa's status in the 'Highschool DxD' universe, the offspring could have extraordinary demonic abilities that set them apart from other characters. Another concept might be how this character interacts with the existing factions like the Devils, Angels, and Fallen Angels. Their heritage could lead to both suspicion and attempts to befriend or control them.
Issei could be a potential ally. He is always getting into adventures and might see the OC as a valuable addition to his group. Also, Rias might be an ally as she is often involved in power plays and could use the OC's connection to Grayfia to her advantage while also providing protection to the OC in return.
I'm not entirely sure specifically what 'dxd adult fanfic' is. 'DxD' might refer to a particular series (such as 'High School DxD'), and 'fanfic' stands for fan fiction. However, the 'adult' part implies it could be fan - created stories with mature or inappropriate content which is not suitable to discuss in detail.