There could be new characters introduced that are related to Quetzalcoatl in some way. They might be students with powers based on Quetzalcoatl's mythology. And of course, the main female characters from DxD would also be part of the story, interacting with these new elements.
The main characters would probably include Rias Gremory as well. She would be involved in the new plotlines that revolve around the quetzalcoatl highschool concept. Her leadership and relationships with other characters would be further explored, especially in the context of this new fanfiction setting which combines the elements of DxD and Quetzalcoatl.
It's likely that the main characters from the original 'Highschool DxD' series would still play important roles. Maybe Issei Hyodo would be there, adapting to the new quetzalcoatl - influenced environment.
In some of these fanfictions, there could be a focus on the mythology of Quetzalcoatl integrated into the Highschool DxD universe. This could lead to exciting tales where the characters have to face off against threats related to this ancient mythology while also dealing with the typical high - school drama and the battles that are characteristic of the DxD world. There might be new magical abilities or artifacts inspired by Quetzalcoatl that change the course of the story.
In addition to Gohan and Issei, Rias could be a main character in this fanfiction. She is a powerful devil and a key figure in the Highschool DxD universe. Her relationship with Gohan could be complex, especially when it comes to power dynamics and her own goals for her peerage. She might be intrigued by Gohan's power and want to recruit him or at least form an alliance with him.
In most shinso vampire Highschool DxD fanfiction, aside from the shinso vampire itself, characters like Akeno Himejima could be main characters. She has her own powers and personality that would interact interestingly with a shinso vampire. Also, Koneko Toujou could be important. Her relationship with the shinso vampire might involve her cat - like nature and her role in the devil society. And of course, there could be original characters created specifically for the fanfiction that become main characters as well.
Typically, you might still see Issei Hyoudou as one of the main characters. His journey could be even more complex in a fanfiction about death and rebirth. He might have to face new challenges related to his own mortality or the rebirth of those around him.
There could be Issei from the 'Highschool DxD' series. He might be involved in the fanfiction, perhaps having a different relationship with Ophis compared to the original series.
Akeno Himejima might be another important character. Her abilities and personality could be explored in relation to the Regulus Nemea elements in the fanfiction. For example, she could be involved in a plot where she uses her skills to help or hinder the progress related to Regulus Nemea, adding depth to the story.
Obviously, the son of Trihexa is one of the main characters. His actions and development would be central to the story. Then there could be characters from the original 'Highschool DxD' series like Issei, who might interact with this new character in various ways, either as an ally or an opponent. Rias could also be a main character as she is an important figure in the original series and her reaction to the son of Trihexa would be significant.
Well, first there's Issei. He's the protagonist, a former human turned devil. Rias Gremory is really important. She's a powerful devil and kind of Issei's mentor in the devil world. Akeno is also a main character. She has a unique personality and is close to Rias. Kiba Yuuto, he's a skilled swordsman among the devils. And Xenovia is interesting too. She starts as an exorcist but then her path crosses with Issei and the others, which changes things for her.
Akeno Himejima is also a key character. She is one of Rias' peerage members and has a complex personality. Koneko Toujou, a cat - like devil, is part of the group as well. She has a strong fighting ability and an interesting backstory.
If Spawn were to interact with the main characters, he would bring a whole new level of seriousness. He has a dark past and a lot of baggage. When it comes to Issei's goal of becoming a harem king, Spawn might find it absurd but also interesting in a way. He could offer his own perspective on power and how to use it responsibly, which would be a contrast to the more carefree attitude of some of the Highschool DxD characters. And with the other characters like Akeno and Koneko, he'd be sizing them up, trying to figure out if they're threats or allies.