One common theme is loyalty. Grayfia is often portrayed as being extremely loyal in these fanfictions, whether it's to her superiors or to her new friends in the high school setting. Another theme is mystery, as her character often has secrets that are slowly uncovered throughout the story.
One common theme is her loyalty. Grayfia is known for her loyalty in the series, and fanfictions often explore this aspect further, like how she balances her loyalty to different characters or factions. Another theme is her power. Writers like to show her using her magic and skills in different situations.
I'm not sure if there is specific fanfiction directly involving both Naruto and Grayfia from Highschool DxD. Fanfiction can cover a vast range of combinations and crossovers, but this particular one might be quite rare. You could try searching on specialized fanfiction websites to see if any exist.
One great piece of highschool dxd grayfia fanfiction is 'Grayfia's New Role'. It explores Grayfia in a different light, showing her dealing with the chaos of the high school environment in the DxD universe. Another interesting one is 'Grayfia and the Mysterious Student' which has a lot of mystery and some great character interactions.
One key point is Grayfia's role as a powerful servant. She often has to balance her loyalty to Sirzechs and deal with the various chaotic situations in the Underworld. For example, she is involved in diplomatic affairs and power plays within the demon realm.
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 way could be through a powerful magic - ninjutsu hybrid spell. Maybe a character with knowledge of both worlds accidentally creates a portal that merges the two. For example, if a shinobi in Naruto world somehow gets hold of a magic item from Highschool DxD and activates it in a wrong way.
The devils who oppose Grayfia's family could be the main antagonists. They might see Grayfia's brother - in - law as a weak link or a potential threat to their power. So they would try to get rid of him or manipulate him for their own gains.
A great plot might be that Grayfia's brother - in - law is actually a half - demon or half - angel who has been hidden away from the main DxD world until now. When he enters the highschool, his presence starts to disrupt the delicate balance between the different species. Some see him as a threat, while others think he could be a key to a new era. As he tries to figure out his own identity and powers, he also has to deal with the normal high school problems like making friends, dealing with bullies, and passing exams in this supernatural high school.
One theme might be about friendship or alliance. Despite their differences, they could form an unlikely bond. Naruto, with his strong sense of justice and determination, and Grayfia, with her loyalty and powers in the Highschool DxD world, could team up against a common enemy. Or it could be a theme of discovery, where they learn about each other's unique abilities and cultures.