History Fanfic / OldLightStillSlantsThrough

* BoxingLessonsForSuperman: After learning that he has Sun Flames, Izuku immediately starts taking first aid classes to help him better utilize its healing abilities once he gets the hang of them.

* HeroicRROD: Not quite as severe as his canon counterpart's, but Izuku's use of Dying Will Flames does do him harm if he's not careful, giving himself frostbite after Tsuna possessed him to freeze the Sludge Villain. [[spoiler:He also gets second degree burns on his right hand after using the X-Burner for the first time, but luckily Recovery Girl was on site.]]

* TheKnightsWhoSaySquee: Izuku is still very much a Hero {{Otaku}} here, clamping his hands over his mouth in excitement while meeting Recovery Girl even when Hyper Dying Will Mode should have kept him calm. He also did this while his hands were on fire.

* MyGodWhatHaveIDone:
** After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. He doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt as he doesn't know what actually happened. He doesn't bother Izuku after that, refusing to even make eye contact with him due to his enduring belief that he almost got someone killed.

** Izuku ''does'' manage to practice his flames by using them to recover from his exhaustion faster and increase his strength somewhat without entering Hyper Dying Will Mode while carting around trash.

* StunnedSilence: Izuku can only stare at Toshinori Yagi when the man expressed his confidence that Izuku will end up at the Sports Festival next year. ''No one'' had ever shown that level of faith in his ability, not even his own mom. Izuku has to force himself [[RealMenDontCry to not cry]] as he bows in gratitude. This also leads Izuku's Hyper Intuition to fail against Toshinori, since this chance meeting made Izuku subconsciously trust him despite barely knowing him.

* SuperiorSuccessor: Tsuna mentions that Izuku is taking to using Hyper Dying Will Mode far more easily than he ever did, since Izuku can potentially enter it at will on his own while Tsuna needed Dying Will Pills to achieve the same result. Izuku is also learning how to use his flames without the aid of a Box Weapon.

** After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. He doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt as he doesn't know what actually happened. He doesn't bother Izuku after that, refusing to even make eye contact with him. Having to deal with the guilt that he almost got someone killed.

* ComboPlatterPowers: Izuku is able to use both Sky and Sun Flames. He can use the flames to increase his strength enough to easily punch through the heads of the Entrance Exam's robots and toss them around, blast and scorch things with fire, freeze them with Zero Point Breakthrough: First Edition, heal himself and others with his Sun Flames, and potentially fly (the author says that Tsuna is intentionally being a {{Troll}} but not telling Izuku about this last one until he absolutely needs it).

* HatesBeingTouched: Years of physical abuse from Katsuki have taken their toll on Izuku here. He doesn't let anyone except for his mom and Tsuna touch him without his express permission, but he ultimately just lets Toshinori [[AffectionateGestureToTheHead ruffle his hair]] after he successfully cleared Dagobah Beach because of how close they've become over the past few months.

** After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. He doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt. He doesn't bother Izuku after that, refusing to even make eye contact with him. Having to deal with the guilt that he almost got someone killed.

* TakeAThirdOption: Without One-for-All, Izuku had three options for dealing with the Zero-Point Robot. The first was to simply run away, letting Uraraka get crushed underneath (which was obviously ruled out). The second was to try and rush in and pull her out while outrunning the robot (again, implausible). So Tsuna presents Izuku with a third option: [[spoiler:Wait until the robot raises its foot into the air, throwing off its balance before blasting it with a full power X-Burner to total it and knock it backward so it doesn't fall on her.]]

** This also means that Katsuki was never attacked by the Sludge Villain. But Izuku's week long absence cause one of his friends to tell someone that Katsuki told Izuku to go jump off the roof when the class was told of how Izuku is at the hospital, and left him with [[MyGodWhatHaveIDone a huge guilt for that action]] after he tried to confront Izuku about his absence later.

* NotGoodWithPeople: In this story, Izuku is generally distrustful of others due to constant bullying all throughout his life. The only ones he pours all of his trust into are his [[MommasBoy mom]], [[SpiritAdvisor Tsuna]], and [[OneHundredPercentAdorationRating All Might]]. This is why he's baffled when he realizes that he trusts Toshinori Yagi, a complete stranger, enough to completely bypass his Hyper Intuition.

** Then Izuku learns that he actually has a hybrid flame like Xanxus', only Sun Flames instead of Storm Flames.

* ForWantOfANail: Since Izuku froze the Sludge Villain solid and was left bedridden for weeks after the incident, he never learns All Might's secret or that All Might and Toshinori Yagi are the same person.
** This also means that Katsuki was never attacked by the Sludge Villain and has little reason to change his behavior.

* MyGodWhatHaveIDone: After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. Then he realizes that Izuku was nearly murdered by a Villain and doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt. He doesn't bother Izuku after that, refusing to even make eye contact with him.

* LivingEmotionalCrutch: Izuku and Tsuna are this to each other. Tsuna relies heavily on Izuku for a sense of normalcy and fulfillment after losing everything, while Izuku relies on Tsuna to ever have a chance of achieving his dream to become a Hero. This goes so far that Izuku promises not to bond with anyone else if it means making sure Tsuna is alright.

The next thing Izuku knows, he's in a hospital, with the police officers telling him that he has an ice Quirk that he used to freeze the Sludge Villain solid. Baffled by this and stricken with new, vivid nightmares filled with fire, Izuku's life only gets weirder when he meets a strange, departed soul named Tsuna in his dreams. This man then offers to teach him how to use a strange power known as "Dying Will Flames", setting the boy off on a path he could have never dreamed of.

Beware of unmarked spoilers

* HyperAwareness: Like Tsuna, Izuku has this while in Hyper Dying Will Mode, as demonstrated while speaking to his mom about his new "Quirk".

'''Narration:''' he reaches down and Tsuna pushes up at the same moment and between one blink and the next, the world is— Clear. Uncomplicated. So easy to understand and react to, because it’s not that the world has slowed down any, it’s that Izuku’s processing has become faster, the streams of information he can take in has increased, and everything is ''there'' for him to take in.

* HurtingHero: Both Tsuna and Izuku have suffered years upon years of bullying, emotional, mental, and physical trauma that continue to plague them to this day.

* MyGodWhatHaveIDone: After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. Then he realizes that Izuku was nearly murdered by a Villain and doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt. He doesn't bother Izuku about that.

* EccentricMentor: Tsuna is more than a little kooky, often getting on his protege's nerves for a quick laugh, joking about things that terrified him in the past (and freak out Izuku) and suffering from emotional breakdowns when he has a particularly painful flashback. The training he puts Izuku through is spartan-like and rigid, much like the regiment Reborn put him through, especially when Izuku is still feeling the effects of the pneumonia he suffered from the Sludge Villain attack. But in the end he cares for Izuku above all else and would like nothing more than for him to succeed and achieve his goals. Izuku might trust Tsuna with his life, but he still thinks the man is "absolutely insane."

* MyGodWhatHaveIDone: After hearing that Izuku ended up in the hospital, Bakugou initially fears that Izuku actually took his advice and tried to kill himself. Then he realizes that Izuku was nearly murdered by a Villain and doesn't bother him until the very end of the day, when Izuku is just so ''tired'' of their daily routine that he refuses to give Bakugou any more information about what happened, leaving him feeling somewhere between anger and guilt.

* {{Reincarnation}}: Izuku is Tsuna's reincarnation, but Tsuna's consciousness is still around to mentor Izuku.

* StepfordSmiler: Tsuna may laugh and joke about the mafia world, but he's far from accepting of his fate and that of the Vongola Familia, having numerous mental breakdowns over the course of the story.

* SuperiorSuccessor: Tsuna mentions that Izuku is taking to using Hyper Dying Will Mode far more easily than he ever did, since Izuku can potentially enter it at will on his own while Tsuna needed Dying Will Pills to achieve the same result. Izuku is also learning how to use his flames without the aid of a Box Weapon, making this even more impressive to Tsuna.

* WrongContextMagic: Izuku hides his newly manifested Dying Will Flames by registering them as a Flame Quirk taking after his father's firebreathing to hide from the Vindice as well as avert lingering suspicions about his sudden new powers.

* AdaptationalJerkass: Izuku is somewhat more resentful and abrasive than in canon, reacting angrily when Toshinori asks Izuku to slow down after a coughing fit in the middle of training. He's also much colder to Katsuki and is perfectly fine with being alone after spending his entire life being picked on. The GhostMemory he inherited from Tsuna doesn't help matters, since he's reminded of all the times Tsuna was called no good and worthless, much like how people look down on him for being Quirkless. That said, he's still ultimately very kindhearted, immediately changing his tone after realizing what he said and going to free the Sludge Villain even as the police officers told him that he didn't have to.

** Then it's Izuku's turn to get one after he's wracked with guilt over leaving the Sludge Villain forzen and forgetting about it, but Officer Tsukauchi has seen this same self-sacrificing and self-destructive mindset with All Might, speaking to the boy to make him feel better and to stop the problem before it gets worse.

-->'''Tsukauchi:''' It was self-defense. You don’t remember it, and you can be excused for not ever wanting to think of it again. When you recalled what we told you about the villain and had a handle on your Quirk, you came here immediately to fix it. Doesn’t seem like a problem to me.\\

* YouAreBetterThanYouThinkYouAre: Izuku is wracked with guilt over leaving the Sludge Villain forzen and forgetting about it, but Officer Tsukauchi has seen this same self-sacrificing and self-destructive mindset with All Might, speaking to the boy in hopes of nipping the problem at its source.

* EccentricMentor: Tsuna is more than a little kooky, often getting on his protege's nerves for a quick laugh, joking about things that terrified him in the past (and freak out Izuku) and suffering from emotional breakdowns when he has a particularly painful flashback. The training he puts Izuku through is spartan-like and rigid, much like the regiment Reborn put him through, especially when Izuku is still feeling the effects of the pneumonia he suffered from the Sludge Villain attack. But in the end he cares for Izuku above all else and would like nothing more than for him to succeed and achieve his goals.
-->'''Narration:''' ''[about cleaning the beach with Dying Will Flames]'' Izuku dislikes everything about this, but he’ll be damned if he’ll give up. Also, he won’t admit it, but he can see how much this will help him. This is just as important for his progress as the other training that Tsuna has him doing, and it’s training his Flames at the same time. He’s not going to say that to Tsuna, though. The man’s absolutely insane.

* HowDoIShotWeb: Even after awakening his Dying Will Flames, Izuku struggles to get them to manifest. Tsuna decides to help him out by acting as a crutch whenever needed, helping Izuku enter Hyper Dying Will Mode and use his fire at will until Izuku no longer needs it.

* EccentricMentor: Tsuna is more than a little kooky, often getting on his protege's nerves for a quick laugh, joking about things that terrified him in the past (and freak out Izuku) and suffering from emotional breakdowns when he suffers flashbacks. The training he puts Izuku through is spartan-like and rigid, much like the regiment Reborn put him through, especially when Izuku is still feeling the effects of the pneumonia he suffered from the Sludge Villain attack. But in the end he cares for Izuku above all else and would like nothing more than for him to succeed and achieve his goals.

* AndIMustScream: When Tsuna briefly takes over Izuku's body, he uses Zero Point Breakthrough: First Edition to freeze the Sludge Villain solid, leaving the villain frozen and unmoving while the Heroes and police took him away. Since the ice is made of Negative Energy, it can only be melted by other Dying Will Flames, potentially leaving the villain trapped permanently since Izuku had no idea how to use his abilities for months and the fact that Dying Will Flames have fallen into obscurity. It takes several months for Izuku to remember the Sludge Villain's fate and go to free it out of his own ChronicHeroSyndrome and [[ItsAllMyFault feelings of guilt]], but Tsuna assures him that it wasn't Izuku's fault and that three months was nothing compared to the decade Tsuna's cousin Xanxus spent on ice.

* ForgotAboutHisPowers: Izuku realizes that he could have passed off his Hyper Intuition as a Quirk if he had just realized that he had it, potentially sparing himself years upon years of torment, leaving him bitter and feeling quite stupid for not realizing this. On the other hand, he may have never met Tsuna if he did.

* SpiderSense: Izuku has inherited Tsuna's Hyper Intuition, giving him an enhanced sense for danger and how to dodge it, with the Sludge Villain attack happening while Izuku was too hung up over his fight with Katsuki to heed his intuition's warnings. Izuku is also baffled about how Toshinori Yagi, a stranger Izuku barely knows, is able to avoid triggering it, unaware of the fact that the skeletal man is actually the hero he looks up to the most, All Might.

* DidntThinkThisThrough: Like All Might in canon, Tsuna has Izuku clear Dagobah Beach of trash to prepare for the U.A. Entrance Exam. Unlike All Might, they didn't make arrangements to transport the trash to the landfill, leaving it in huge piles until Toshinori comes along to offer a pickup truck to help out ([[HypocriticalHumor only to realize after offering that he doesn't have a pickup truck]]).

* ForgotAboutTheirPowers: Izuku realizes that he could have passed off his Hyper Intuition as a Quirk if he had just realized that he had it, thus avoiding years upon years of bullying, leaving him bitter and feeling quite stupid for not realizing this. On the other hand, he may have never met Tsuna if he did.

* SoleSurvivor: In contrast to what happened during the Future Arc of his home series, Tsuna is heavily implied to have been the last of the Vongola to fall, having watched his little brother, who was only 19 at the time, die right in front of him.

* AdaptationalJerkass: Izuku is somewhat more resentful and abrasive than in canon, reacting angrily when Toshinori asks Izuku to slow down after a coughing fit in the middle of training. He's also much colder to Katsuki and is perfectly fine with being alone after spending his entire life being picked on. The GhostMemory he inherited from Tsuna doesn't help matters, since he's reminded of all the times Tsuna was called no good and worthless, much like how people look down on him for being Quirkless. That said, he's still ultimately very kindhearted, apologizing to Toshinori for being rude and going to free the Sludge Villain even as the police officers told him that he didn't have to.

* DissonantSerenity: Tsuna has been so thoroughly broken by his experiences that he's able to mention how Reborn used to shoot him with Dying Will Bullets to get him to enter Dying Will Mode with a smile on his face. Izuku is thoroughly unnerved by this, as it reminds him that Tsuna was a mafia boss.