Issei is often involved as he is one of the central characters in the Highschool DxD universe. His character can be greatly influenced by hypnosis, either being the one using it or being affected by it.
Rias Gremory might also be a main character in such fanfiction. Her leadership role and powerful nature could be intertwined with the hypnosis concept. Maybe she uses hypnosis to enhance her devil clan's power or to outwit her enemies.
Obviously, Escanor is a main character. He is often the center of the story due to his powerful presence. In addition, characters from the original Highschool DxD like Issei might also be involved. Issei could be a friend or a rival to Escanor in the fanfiction, adding an interesting dynamic as Issei is known for his own growth and development in the original series.
Well, considering the nature of 'highschool dxd', characters like Xenovia could be involved in the 'ultimate hypnotism fanfiction'. Her strong will and combat skills might make her a target for hypnotism to be subdued or she could be the one trying to resist hypnotic control. Also, Asia, with her kind and gentle nature, could be a character that gets caught up in the hypnotism plot, either being hypnotized to do things against her will or being the one to break free from it and help others.
Issei is often involved. Since he has a connection to the Gremory family through Rias, his actions and decisions can sometimes be a part of the Gremory - bashing scenarios. Another could be Sona, as her family has a relationship with the Gremorys and she might be in a position where she has to take a stance against them in some fan - created situations.
Rias Gremory could also be a main character. Her relationship with Issei and her role as a devil leader means she can play a crucial part in fanfictions about the One Winged Angel. She might be involved in helping Issei master the form or dealing with the consequences of its appearance.
Rias Gremory is often a popular character in such fanfics. Given her central role in the original Highschool DxD series, her relationship with Issei could be explored in the context of a pregnancy. Her status as a devil and the leader of her peerage would add a lot of complexity to the story if she were to become pregnant.
The dragonborn himself is, of course, a main character in these fanfictions. Depending on the story, other DxD characters like Akeno Himejima could also be involved. She has her own powers and personality, and her interactions with the dragonborn can add a lot of depth to the story. Her seductive nature might play off against the dragonborn's more straightforward and perhaps stoic personality.
Naruto himself is often involved. His strong will and determination could make him either a target of hypnosis or someone who has to resist it. Sasuke is also a likely candidate, given his powerful doujutsu, the Sharingan. Hypnosis could potentially be used to manipulate his actions or unlock hidden aspects of his Sharingan powers.
Harry Potter himself is often involved. Writers might explore how he could be hypnotized to face his inner demons or unlock new powers. Hermione is also a popular choice as her intelligence could be enhanced or her memories explored through hypnosis.
One interesting plot could be the main character using hypnosis to gain unique powers in the Highschool DxD universe. For example, they might hypnotize enemies to make them fight for their side during battles.
Definitely Midoriya. He's such a central figure that it's easy to imagine how hypnosis could play into his story. He could be hypnotized to doubt his own abilities or, on the flip side, be hypnotized to unlock new levels of his quirk. Ochaco Uraraka is another character who could be involved. Her zero - gravity quirk could be manipulated through hypnosis. For example, she could be hypnotized to lose control of her quirk in a dangerous situation or be made to use it in a more powerful and unexpected way.