In Gohan High School DxD fanfiction, there could be a concept of Gohan's academic influence. Gohan is a very intelligent character. He might introduce new scientific ideas or study techniques to the students at the high school in the DxD world. This could lead to different character developments, as some characters might be inspired to pursue knowledge more seriously, and it could also affect the relationships between different factions in the story, as knowledge could be seen as a form of power.
In a Gohan in High School DxD fanfiction, Gohan could be a special exchange student. He has to balance his studies and his new life in this strange world filled with devils and angels. He might start a martial arts club in the school, which becomes popular. But his real purpose could be to find a way to bring peace between the different factions, using his Saiyan abilities and kind heart.
A great plot could involve a tournament in the High School DxD world that Gohan participates in. He teams up with some of the characters from that series. His different fighting style and abilities would shock everyone. There could be some sort of mystery or conspiracy behind the tournament as well, and Gohan's integrity and sense of justice would drive him to uncover the truth.
One popular pairing could be Gohan and Rias. Their personalities are quite different, with Gohan being more reserved and Rias being a strong - willed devil. The contrast between their powers and backgrounds could create an interesting dynamic in the fanfiction.
A Naruto - High School DxD fanfiction with the concept of immortality could start with Naruto being summoned to the DxD world by an unknown force. Since he's immortal, he doesn't fear death like many in the DxD world do. This could lead to him taking on more dangerous quests or getting involved in the wars between the different species. He could also use his immortality to experiment with different powers and techniques in the DxD world without the risk of dying, which would make him a very formidable and unpredictable character.
Gohan and Issei would be really interesting. Issei is all about being a pervert and getting stronger in his own way. Gohan is this powerful yet humble Saiyan. Their different outlooks on power and relationships would create a lot of humorous and thought - provoking moments.
A great idea for a High School DxD fanfiction is to explore a romantic relationship that is not the typical one in the series. For instance, a story about a relationship between two side characters who have to overcome many obstacles due to their different species or social status within the devil - angel - fallen angel hierarchy. You could also write about a character's journey of self - discovery outside of the main plot of the series. Like a character who realizes they have a different purpose in life than what they were initially led to believe.
One interesting 'High School DxD' fanfiction could be those that explore different relationships between the main characters. For example, some might focus on the growth of Issei's relationship with Rias in a more in - depth way than in the original series, showing their daily interactions and how they overcome new challenges together.
One interesting storyline could be Alucard forming an unexpected alliance with the main characters in High School DxD. Maybe he uses his unique powers to help them in a battle against a common enemy.
One interesting fanfiction could be a crossover where Naruto characters end up in the High School DxD world and have to adapt to the different rules and powers there. For example, Naruto might use his chakra in unique ways against the devils and angels in the DxD universe.
One interesting crossover could be the sharing of power concepts. For example, Naruto's chakra system might interact in unique ways with the devil powers in High School DxD. Maybe a character could combine Naruto's Rasengan with a devil's special attack.