In a world of Sacred Gears, Magic, and Quirks, Izuku Mirodiya was considered useless, until he met All Might. He was also considered human, until he met Ochako Uraraka, who saved his life at the cost of turning him into a devil.
A Deku with the Devil
is a My Hero Academia/High School D×D crossover fic by The_Mad_Mystic on Archive of Our Own.
Izuku Midoriya was considered useless, due to his lack of a Quirk, something eighty percent of the world's population does have, but he doesn't let that deter him from his dream of becoming a Pro Hero. A casual encounter with All Might, Japan's Number One Hero, allowed him to not only gain a Quirk, but also the chance to achieve his dream.
However, during the U.A. Entrance Exam, after saving a girl called Ochako from a giant robot, his use of his Quirk ends up overwhelming his heart, leaving him on the edge of death. With no other choice if she wants to save his life, Ochako reincarnates her savior into a devil, as part of her Peerage. Izuku revives, and now the two of them have to deal with the consequences of the choice, a society that remains untrustful of the magical world and their future as heroes.
This story has examples of the following:
- Adaptation Relationship Overhaul:
- All Might met Inko while he trained Izuku.
- Izuku met Iida Tenya before U.A., and became friends with him. Unfortunately, by the time U.A. begins, Tenya turned his back on Izuku due to his hatred of devils, even saying that Izuku is nothing more than a monster wearing his dead friend's skin.
- Adaptation Species Change:
- Ochako is a half-devil hybrid, while her mother is a full High-Class devil.
- Izuku and Tokoyami become reincarnated Devils in Ochako's Peerage.
- Whatever species Nezu is in canon, he sure is far away from being the Eldritch Abomination he's here.
- Adaptational Early Appearance:
- Ochako's parents appear shortly after the entrance exam.
- Eri and Overhaul show up even before Izuku and Ochako begin attending U.A.
- Izuku meets Todoroki before U.A. as part of one of his contracts.
- Monoma and Shinso are part of 1-A.
- Adaptational Nice Guy: Endeavor is a better person all around, based on his one scene - which implies that the Todoroki family is better adjusted.
- Age Lift: The students are a couple of years older than in canon.
- Ascended Extra: Hitoshi Shinso and Neito Monoma join 1-A.
- Awesomeness by Analysis: Izuku uses his Quirk-analyzing skills to help heroes learn how to improve their Quirk use. The Cash he earns from this is enough to pay for a penthouse in a very exclusive high-rise building.
- Broken Masquerade: Humanity knows, by and large, about the supernatural.
- Broken Pedestal:
- Izuku once considered Eraserhead one of his favorite heroes. Then he met him, and saw his Fantastic Racism towards Devils.
- Mirio is heavily disappointed with Sir Nighteye when he learns about the latter's plans to have All Might pass One for All to him.
- Continuity Cameo: Rias and Issei show up in Chapter 9, with the former being Ochako's friend and the latter being Kaminari's.
- Demoted to Extra: Bakugo's only appearance is in Chapter 1, before the exam takes place. It is unknown if he was moved to 1-B or just didn't pass the exam.
- Emergency Transformation: Ochako turned Izuku into a Devil to save his life in the Entrance Exam.
- Fantastic Racism: Due to details that are revealed as the story passes, it turns out that a good part of humanity holds this against devils, fallen, and angels.
- Aizawa, in particular, has heavy dislike of devils, believing them to be inherently untrustworthy due to the ones he has met during his work (mostly Stray Devils). He tries to find a way that will allow him to expel Ochako and Izuku without causing troubles for him, and fully expects their classmates to shun them both when their situation is revealed.
- Ochako mentions that few people are willing to hire her father's company due to his marriage to a devil, while her mother's family remains a background threat.
- Iida declares that the Izuku he was friends with died and was replaced with something wearing his skin.
- Freudian Excuse: Aizawa's hatred of devilkind comes from how several Stray Devils killed his friend Oboro.
- Go Look At The Distraction: During the Heroes vs Villains class, Ashido and Kirishima leave tracks to make Asui and Shinso think the bomb is in one of the upper floors, when it's actually behind the first-floor staircase.
- Great Offscreen War: There were at least two between humanity on one side, and the supernatural factions on the other - the Supernatural Wars. All Might made his debut by participating in the Second Supernatural War, single-handedly fighting entire hordes of enemies.
- Half-Human Hybrid: Ochako has a human father and a High-Class devil mother.
- Happily Adopted: After getting her out of Overhaul's grasp, Izuku and Ochako end up adopting Eri.
- Heart Is an Awesome Power: When Izuku meets Issei, the latter still thinks that his Sacred Gear is a Twice Critical. While Issei is a bit bummed about it, Izuku points out that doubling your base strength is actually pretty useful if you train up said base strength enough.
- Hoist by His Own Petard: All Might points out to Aizawa that him unfairly singling out Izuku and Ochako makes them look like victims and him the villain, which will cause his other Hero students to flock to their side as they are seeing their teacher commit an injustice, which is the exact opposite of what he wants.
- Hormone-Addled Teenager: Izuku and Ochako, particularly after the first time they have sex.
- Huge Girl, Tiny Guy: Ochako's parents.
- Irony: Izuku's first thought about Ochako is that she must be an angel. It turns out she's a devil.
- "It" Is Dehumanizing: Iida calls post-reincarnation Izuku a "thing wearing [Izuku's] skin".
- Laser-Guided Amnesia: Eri has been subconsciously using her Quirk on herself to erase her traumatizing memories of Overhaul.
- Loophole Abuse:
- Ochako's first rule for her Peerage's contracts is that people must always pay the price for summoning them no matter what, and the second is that they can reject contracts they don't feel comfortable with. Izuku uses them to take Eri away from Overhaul without having to fulfill the contract (which consisted of him providing Overhaul with as much of Eri's blood as possible, with Overhaul offering up Eri herself as a payment). Overhaul missed this loophole because he only skimmed the contract instead of reading it thoroughly.
- Since Izuku and Ochako are counted as the same person for the purpose of marks and school events, 1-A has 21 students instead of 20.
- Mutually Exclusive Magic: If someone has a Quirk, they won't get a Sacred Gear, and viceversa. Some experiments have been made trying to implant a Sacred Gear into someone with a Quirk, but all that does is kill them, and no one knows why.
- Never My Fault: When Mirio tells Sir Nighteye off over the issue with One for All and breaks his working relationship with the man, Nighteye blames Izuku.
- Nightmare Fetishist:
- Eri's favourite movie genre? Horror. Izuku believes it's because of the
Catharsis Factor it provides her after all the stuff Overhaul put her through. - When he learns that Ochako is a Devil King, Tokoyami asks if he can join her peerage. Although she initially refuses on basis that she would have to get to know him more, he eventually gets her to let him become her Rook.
- Eri's favourite movie genre? Horror. Izuku believes it's because of the
- Noodle Incident: The year before starting at U.A., Kaminari short-circuited Kuoh High's electrical system while a group of girls was getting dressed in the locker rooms. It's implied that the girls had to run from the lockers because of this.
- Oh, Crap!:
- Overhaul when Izuku smirks at him and tells him to read through the contract.
- Aizawa is scared out of his wits when he realizes that Izuku is All Might's son.
- Self-Fulfilling Prophecy: Discussed. As All Might points out, Aizawa treating Ochako as if she were a villain just because of her heritage might end up causing her to become one.
- She Is the King: Ochako is the King of the Peerage, with Izuku being a Gender-Inverted example as Ochako's Queen.
- Side Bet: Inko and Ochako's parents make one on how long it will take their kids to get together. Ochako's dad wins.
- Therapy Is for the Weak: Nezu cites this as the reason why Aizawa doesn't want to go to therapy.
- Training from Hell: Izuku went through one in order to train his body so he could adapt to receive One for All. When Fumikage goes through the training routine Izuku went through at the beginning, he's left completely spent and in considerable pain.
- Underestimating Badassery: After Fumikage's reincarnation, Izuku offers him his old training routine, which might be fine. Fumikage states he'll be fine with it. At the end of the day, he's pretty much a giant ache and he realizes how much he underestimated Izuku.
- We Used to Be Friends: Izuku is crushed when he realizes that Iida doesn't consider him his friend on the basis of his resurrection.
- What the Hell, Hero?:
- All Might calls Aizawa out for his Fantastic Racism several times.
- Mirio does this to Sir Nighteye when he learns about One for All and his mentor's attempts to make All Might pass it to him.
