History Fanfic / DekiruTheFusionHero

* TongueTrauma: What happens when [[spoiler: Tsuzuru]] takes a long fall and tries to catch herself with her OverlyLongTongue while remembering that Tsuyu's tongue isn't sticky enough to catch - and jerking to a sudden halt when it does catch thanks to [[spoiler: Minoru's added stickiness to the fusion's Quirk]].

* AdultFear: The first time Izuku and Katsuki fused into Katzuku, it terrified their mothers, whose sons had seemingly disappeared and left a completely unknown boy in their place. Even after figuring out what happened, their terror remained due to the possibility that the fusion might have been permanent.

** Fusions with Momo and Mina are both girls as well, leading Katsuki to declare that the gender of his Human Fusion partner determines the fusion's gender, so any time he fuses with a girl will result in this. [[spoiler: Three-person fusions are more problematic, since while Tsuzuru (Izuku, Tsuyu, Minoru) is a girl, Katzuchako (Katsuki, Izuku, Ochako) is a boy.]]
* GodzillaThreshold: [[spoiler:During the USJ arc, Izuku initiates a second triple-fusion with Katsuki and Ochako, despite having only just learned he could do that ''on that day'' (and by accident, no less), to hold off Nomu until help arrives. He knows he's risking severe, potentially fatal, exhaustion in doing so, but the circumstances are so dire that it was the only option available if all of Class 1-A (including Aizawa and Thirteen) were to survive]].

** The Sludge Villain easily restrains Katsuki and wards off Izuku, like in canon. Katzuku, meanwhile, easily blows him apart with one explosion.
** Izuku and Momo were on the losing end of the Heroes vs. Villains exercise against Shoto and Tenya, two of the strongest students in Class 1-A. When they merge into Moku, however, the tables turn immediately and they curb-stomp both in quick succession.

* ZergRush: The League of Villains during the USJ incident. As the students note, most of them are two-bit thugs that even they can handle; however, there's so many of them that it's actively preventing Class 1-A from reuniting at the entrance.

* ZergeRush: The League of Villains during the USJ incident. As the students note, most of them are two-bit thugs that even they can handle; however, there's so many of them that it's actively preventing Class 1-A from reuniting at the entrance.

* ElementalBaggage: As shown during Aizawa's test, Izuku needs quite a lot of material on hand to absorb to fully transform, else he can only manage {{Partial Transformation}}s. However, Momo Yaoyorozu can easily provide said material, making her Quirk a perfect complement to his.

* FailedASpotCheck: Katsuki and Izuku are so glued at the hip neither notice the [[OhCrap memory sharing]] aspect of Fusion until after Ochako knows about All-Might. They're only able to confirm it by checking to see what each other had for breakfast.

*** During the USJ arc, [[spoiler:Izuku finds he can create three-person fusions, which he does with Minoru and Tsuyu, and then later on with Katsuki and Ochako]].
* GenderBender: Since the resulting fusion between Izuku and Ochako is a girl, Mitsuki points out that, by extension, Izuku turns into a girl when fused with Ochako.

* HourOfPower: Izuku cannot hold a fusion (material or human) for more than a while before separating, though practice slowly builds up the limit. It's also implied that it's based on stamina, as using draining moves (like One For All) can shorten the timespan.

* LogicalWeakness: When using Fusion on inanimate materials, Izuku is only able to fully transform himself if has [[ElementalBaggage enough material to do so]], and he's only as tough as said materials. The converse is also true: there is only so much of his body that he can merge material with, so if the source of the material is too substantial (like, say, the large and thick metal doors of the USJ), he can't absorb all of it.

* MentalFusion: A fusion merges personality traits from both Izuku and whoever he fuses with. In Izuku's case, this means that the majority of the fusions have a tendency to MotorMouth (whether boastfully like Katsuki, outgoing like Ochako, or [[GenkiGirl exuberantly]] like Mina) and call Katsuki "Kacchan".

*** On top of that, it seems that people who fuse with Izuku adopt some of his personality traits and [[JustForPun quirks]] (But not the other way around). Ochako and Momo started calling Katsuki "Kacchan" (much to the latter's utter annoyance) like Izuku does, and Tsuyu started to develop a crush on Ochako.

* {{Stripperiffic}}: Izuku' first costume is an accidental version of this. The silver areas are actually woven metal that he can fuse with, but when he designed it he failed to take into consideration exactly how much fabric would be left after he absorbed the metal. It still covers enough of him to not be indecent though.

* VitriolicBestBuds: AdaptationalNiceGuy he may be, but this is still [[JerkWithAHeartOfGold Katsuki]] we're talking about. He still considers Izuku and Ochako his rivals, and the two aren't averse to throwing barbs back at him. Despite this, Katsuki and Izuku are practically brothers, and Katsuki and Ochako form a minor friendship in the time before the semester begins.

* DramaPreservingHandicap: Using Fusion to boost Izuku's durability means that using One For All won't destroy his arms every time he uses it, so that's a plus. However, it seems to also limit its power somewhat, keeping him from just using a MegatonPunch with every blow. He can still launch extremely powerful blows, what would normally be considered a MegatonPunch and what would have outright crippled his arms after one use in canon, but it's not the OneHitKO that it normally is.

* EmergencyTransformation: Non-permanent variant - [[spoiler:Izoru, Izuku and Minoru's Fusion, fusing ''again'' with Tsuyu to save her from Shigaraki's [[MakeThemRot touch]]]].

* NormalFishInATinyPond: Played with in regards to Shoto. While he's still the strongest student in Class 1-A in terms of raw power, all of them still have versatile and unique quirks that are better for other aspects of hero work than his would be. Then there's Izuku's fusions, which not only surpass Shoto in power but also make his classmates' quirks even more versatile, completely upstaging Shoto in turn.

** Just like in canon, one of the top students of Class 1-A eats a big helping of HumblePie after losing the Heroes vs. Villains exercise. Though, in this case, it's not Katsuki (whose ego is much more manageable compared to canon), but instead Shoto, who is defeated by the fusion of Izuku and Momo. Shoto was even teamed with Tenya, like Katsuki was in canon.

* PrideBeforeAFall: Instead of Katsuki like in canon, this happens to Shoto during the Heroes vs. Villains exercise. He arrogantly believed that his ice would be enough to win the match for his team within the first minute, like he did in canon. Instead, Momo and Izuku manage to bypass his ice easily. Once he realizes that failed, he sends Tenya out to fight them while he creates a massive and thick ice room to surround him as he guards the bomb, convinced ''that'' will be able to hold them off. He was correct... until they fused into Moku. Moku promptly defeats Tenya, then destroys the supports of the top floor of the building, sending his ice room flying into the air, where it breaks apart upon contact with the ground. Moku then captures the now freed bomb with seconds to spare. [[TranquilFury Shoto doesn't take the loss well, to say the least]], especially after he learned it was a fusion of Momo and Izuku that won the match in place of them.

** Katzuku's High-Ex mutation is a stronger version of Katsuki's [[HavingABlast Explosion]] Quirk, and they can bypass the limitation that makes it so that they have to secrete the nitroglycerin sweat via their palms and sweat it from ''anywhere''.

** [[spoiler: Tsuzuru, Izuku's Fusion with both Minoru ''and'' Tsuyu, imbues Tsuyu's frog mucus and saliva with Minoru's stickiness, rendering it nearly invisible and strong enough to incapacitate the anti-All Might Nomu]].

* DrawAggro: This is Katsuki and Ochaco's strategy in the Heroes vs. Villains exercise: Katsuki assaults the villains from the front and gets them to focus on him, Ochaco sneaks in through a window and captures the weapon. Interestingly enough, in canon that's what Izuku and Ochaco did ''against'' Katsuki, exploiting his LeeroyJenkins tendencies.

** Katsuki is so [[WeNeedADistraction distracting]] to their foes during the Heroes Vs. Villains exercise that Ochaco was able to simply float herself up into the bomb room through a window and over their heads to the bomb, and Sato and Koda didn't notice until the match was already over.

** His friendship with Ochaco accelerates even faster than it did in canon, to the point that she can be considered his best friend after Katsuki in a mere matter of weeks.

** Sato is the one who escapes from the USJ attack to warn the faculty instead of Tenya, which means that help takes longer to arrive since Sato doesn't have Tenya's SuperSpeed. Tenya is instead sent to the landslide zone, in place of Katsuki. [[spoiler:As a result, All Might isn't there in time to defeat Nomu, forcing Izuku to initiate a second triple-fusion with Katsuki and Ochaco to hold Nomu off until help arrives]].

*** During the USJ arc, [[spoiler:Izuku finds he can create three-person fusions, which he does with Minoru and Tsuyu, and then later on with Katsuki and Ochaco]].

* GodzillaThreshold: [[spoiler:During the USJ arc, Izuku initiates a second triple-fusion with Katsuki and Ochaco, despite having only just learned he could do that ''on that day'' (and by accident, no less), to hold off Nomu until help arrives. He knows he's risking severe, potentially fatal, exhaustion in doing so, but the circumstances are so dire that it was the only option available if all of Class 1-A (including Aizawa and Thirteen) were to survive]].

* JumpedAtTheCall: Mina is actually really unexpected for Izuku, as she's the first person to actually volunteer to fuse with him. Katsuki fused with Izuku first on accident, Ochaco was fused with to save her from the zero-pointer, and Momo did accept, but Izuku offered first.

* PrideBeforeAFall: Instead of Katsuki like in canon, this happens to Shoto during the Heroes vs. Villains exercise. He arrogantly believed that his ice would be enough to win the match for his team within the first minute, like he did in canon. Instead, Momo and Izuku manage to bypass his ice easily. Once he realizes that failed, he sends Tenya out to fight them while he creates a massive and thick ice room to surround him as he guards the bomb, convinced ''that'' will be able to hold them off. He was correct...until they fused into Moku. Moku promptly defeats Tenya, then destroys the supports of the top floor of the building, sending his ice room flying into the air, where it breaks apart upon contact with the ground. Moku then captures the now freed bomb with seconds to spare. [[TranquilFury Shoto doesn't take the loss well, to say the least]], especially after he learned it was a fusion of Momo and Izuku that won the match in place of them.

** This actually ends up hurting them in the long run. Since they're ''such'' good friends, they spend literally almost all their time together. When Izuku fuses with Ochaco to make Izuchako, they don't realize that memories are shared between the fusion's components because for the most part, there wasn't any overlap - they spend so much time together their memories are nearly identical. They check by trying to remember what the other had for breakfast.

** Izuna (Mina Ashido): "Acid Control." Can excrete acid, but can excrete far more than Mina can and the viscosity of the acid can be manipulated after it has been administered on-command.

* AdaptationalNiceGuy: Bakugo is much nicer in this fic, as a result of Izuku developing a Quirk when they were kids and others ''still'' bullying him for it, Bakugo became Izuku's OnlyFriend for a long time. While he can still be a {{jerkass}} in the present, he comes across more as a JerkWithAHeartOfGold to Izuku and, later, Ochako.

** Katzuku (Katsuki Bakugo): "High-Ex." Same explosive ability as Bakugo, but the explosive sweat can be excreted from any part of his body and is twice as powerful.

** Izoru (Mineta Minoru): "Sticky Bomb." The orbs at the end of Izoru's hair explode upon impact, creating a shower of super-sticky fluid that glues any touching objects together except for himself at his own choosing. Izuru can also determine the size of the orbs prior to plucking them from his hair, though larger orbs take longer to create.
** Tsuzuru (Tsuyu Asui and Minoru Mineta): "Sticky Mucus." Tsuzuru's body naturally creates a clear variant of Izuru's Sticky Bomb solution, nearly invisible but just as strong. It is naturally part of her saliva and can be secreted from her skin.

* CastFromStamina: It's implied that how long Izuku can stay in a fused state is based on stamina, as especially draining moves can eat through his [[HourOfPower transformation time]] faster than is normal. [[spoiler: Three-person fusions seem particularly bad about this, when Tsuzuru reverts back to Izuku, Mineta, and Tsuyu, the latter two are tired and sore, but it pales in comparison to Izuku's state, as he's ''literally steaming'' and covered in sweat and reddened skin, though he recovers quickly, and feels like he's just been training for ''hours'']].

** Izuku had his hero suit designed so that he'd have enough metal to fuse with his entire body at any time, but he didn't realize that doing so would consume most of the substance of the suit and leave him largely ExposedToTheElements, which is a problem in the Heroes vs. Villains exercise, where he's paired off with Momo against [[AnIcePerson Todoroki]]. All Might caught this but decided to let him discover it himself so that it'd be a learning experience for him.

** Shoto himself just froze the entire building without thinking of a backup plan if the other team had a way to bypass this despite Iida trying to convince him to come up with one before they started.

* DrawAggro: This is Bakugo and Uraraka's strategy in the Heroes vs. Villains exercise: Bakugo assaults the villains from the front and gets them to focus on him, Uraraka sneaks in through a window and captures the weapon. Interestingly enough, in canon that's what Midoriya and Uraraka did ''against'' Bakugo, exploiting his LeeroyJenkins tendencies.

* EmbarrassingNickname: Bakugo barely tolerates Izuku calling him "Kacchan", but he absolutely hates when everybody else starts doing it.

** Katsuki is so [[WeNeedADistraction distracting]] to their foes during the Heroes Vs. Villains exercise that Uraraka was able to simply float herself up into the bomb room through a window and over their heads to the bomb, and Sato and Koda didn't notice until the match was already over.

** Bakugo is on much better terms with Izuku here, and Izuku's presence has helped curb his more aggressive tendencies.

** Thanks to having Ochako and Bakugo as his sounding boards, Izuku's costume design is slightly different than in canon. In particular, the hood and mouth guard are absent due to them noticing he'd look like an All Might copycat, and most of the material is composed of woven metals. Visually, its described as being nigh-identical to his alpha costume in canon, simply without the mask and hood.
*** Likewise, Ochako and Bakugo have their costumes altered. Ochako's suit is more form-fitting to allow for easier movement with her Quirk, and Bakugo has several smaller bomb tanks on his gauntlets instead of one big one.
** The Hero vs. Villain exercise has several changes to the teams this time around. Izuku is partnered with Yaoyorozu this time, while Ochako is partnered with Bakugo. This in turn causes Iida to be partnered with Todoroki, and Mineta to be partnered with Shoji.
*** The first match is also different. Iida and Izuku are in the same roles as canon, whereas Todoroki is on the villain team this time, while Yaoyorozu is on the hero team.
** Thanks to fighting Iida in melee combat during the Hero vs Villain exercise, Yaoyorozu is made painfully aware of her lacking skill in hand to hand combat compared to her contemporaries.
** Sato is the one who escapes from the USJ attack to warn the faculty instead of Iida, which means that help takes longer to arrive since Sato doesn't have Iida's SuperSpeed. Iida is instead sent to the landslide zone, in place of Katsuki. [[spoiler:As a result, All Might isn't there in time to defeat Noumu, forcing Izuku to initiate a second triple-fusion with Katsuki and Ochaco to hold Noumu off until help arrives]].

** Fusions with Momo and Mina are both girls as well, leading Bakugo to declare that the gender of his Human Fusion partner determines the fusion's gender, so any time he fuses with a girl will result in this. [[spoiler: Three-person fusions are more problematic, since while Tsuzuru (Izuku, Tsuyu, Minoru) is a girl, Katzuchako (Katsuki, Izuku, Ochako) is a boy.]]
* GodzillaThreshold: [[spoiler:During the USJ arc, Izuku initiates a second triple-fusion with Katsuki and Ochaco, despite having only just learned he could do that ''on that day'' (and by accident, no less), to hold off Noumu until help arrives. He knows he's risking severe, potentially fatal, exhaustion in doing so, but the circumstances are so dire that it was the only option available if all of Class 1-A (including Aizawa and Thirteen) were to survive]].
* GoodThingYouCanHeal: Trapped in [[spoiler: Tsuzuru's]] adhesive that no-one can get out of, the Noumu proceeds to just rip off its trapped flesh and let its regeneration take care of it.

* JerkassHasAPoint: Bakugo is more of a JerkWithAHeartOfGold here, but he still makes some good points.

** When they realize that All Might used up his available time in his hero state before the training mission at the USJ, Bakugo calls him an idiot, pointing out that, unless some major incident happened that they somehow didn't hear about in the news, nothing happened where he ''needed'' to pitch in, especially since he knew what the class was doing that day, so he should have had some time left for it. Izuku, try as he might, can't supply a good defense for his mentor.
* JumpedAtTheCall: Mina is actually really unexpected for Izuku, as she's the first person to actually volunteer to fuse with him. Bakugo fused with Izuku first on accident, Uraraka was fused with to save her from the zero-pointer, and Momo did accept, but Izuku offered first.

*** On top of that, it seems that people who fuse with Izuku adopt some of his personality traits and [[JustForPun quirks]] (But not the other way around). Ochako and Momo started calling Bakugo "Kacchan" (much to the latter's utter annoyance) like Izuku does, and Tsuyu started to develop a crush on Ochako.
* NotQuiteDead: The Anti-All Might Noumu has just been dumped into USJ's lake [[CementShoes glued to a mass of metal]], with no way for him to escape. Then Kurogiri retrieves his body from the lake, and it looks like he has drowned. Then he twitches.

*** Izuku, Minoru and Tsuyu when Kurogiri overhears Minoru mentioning where the Noumu was, which allows him to retrieve him.
*** Then a MassOhCrap version when the Noumu who looks like he had drowned in the lake turns out to still be alive.

* TheRival: Bakugo has two this time around: Izuku as the holder of One For All and the person he strives to keep ahead of, and Ochako for edging him out as the highest scorer in the U.A. entrance exam (since she was given Izuchako's Rescue Points alongside Izuku).

* StatingTheSimpleSolution: When Todoroki freezes the building in the Heroes vs. Villains exercise, Momo just makes ice skates at Izuku's suggestion. She's actually a little embarrassed that she didn't think of it herself, especially since she's had skating lessons. Izuku, for his part, is durable and strong enough in his metal form to simply barge through the ice by himself.

** [[spoiler: Tsuzuru, Izuku's Fusion with both Minoru ''and'' Tsuyu, imbues Tsuyu's frog mucus and saliva with Minoru's stickiness, rendering it nearly invisible and strong enough to incapacitate the anti-All Might Noumu]].

** During the first Hero Class and the Hero vs. Villain exercise, Izuku thinks he'll be okay as long as he is on a team with Bakugo or Ochako who he can fuse with without any drama. Guess who's not only ''not'' on his team, but paired up with one another?
** When asked where the Noumu went, Minoru eagerly exclaims that [[spoiler: their triple-fusion with Tsuyu, Tsuzuru, dropped him into the lake glued to a mass of steel]]. Unfortunately, Kurogiri hears him and makes a [[ThinkingUpPortals portal]] to get him out.
* VitriolicBestBuds: AdaptationalNiceGuy he may be, but this is still [[JerkWithAHeartOfGold Bakugo]] we're talking about. He still considers Izuku and Ochako his rivals, and the two aren't averse to throwing barbs back at him. Despite this, Bakugo and Izuku are practically brothers, and Bakugo and Ochako form a minor friendship in the time before the semester begins.
** This actually ends up hurting them in the long run. Since they're ''such'' good friends, they spend literally almost all their time together. When Izuku fuses with Uraraka to make Izuchako, they don't realize that memories are shared between the fusion's components because for the most part, there wasn't any overlap - they spend so much time together their memories are nearly identical. They check by trying to remember what the other had for breakfast.

** Human Fusion is treated like this. While it isn't explicitly ''forbidden'', it's unpredictable nature means it's best used only as a last resort. Not to mention that prior to gaining some tips from Mandalay, he ran the risk of exposing All Might's secret due to the its MentalFusion nature. [[spoiler:Notably, the first time Izuku starts spamming the technique in a short time-frame is during the USJ arc, which is an explicit life-or-death situation]].

** Human Fusion is treated like this. While it isn't explicitly ''forbidden'', it's unpredictable nature means it's best used only as a last resort. [[spoiler:Notably, the first time Izuku starts spamming the technique in a short time-frame is during the USJ arc, which is an explicit life-or-death situation]].

* SoreLoser: [[spoiler:After his plan fails on every level, Shigaraki decides bail with Kurogiri...but not before leaving Nomu behind to kill everybody in the USJ]].

[[https://www.fanfiction.net/s/13128563/1/Dekiru-The-Fusion-Hero Dekiru: The Fusion Hero!]] [[https://archiveofourown.org/works/17413937/chapters/40990907 (AO3 link)]] is a ''Anime/MyHeroAcademia'' fanfiction by [[https://www.fanfiction.net/u/3217679/l-OmegaInfinity-l | OmegaInfinity |]] where Izuku can fuse himself with inanimate materials and other people.

* GodzillaThreshold: [[spoiler:During the USJ arc, Izuku initiates a second triple-fusion with Katsuki and Ochaco, despite having only just learned he could do that ''on that day'' (and by accident, no less), to hold off Noumu until help arrives. He knows he's risking severe, potentially fatal, exhaustion in doing so, but the circumstances made it the only option available if all of Class 1-A (including Aizawa and Thirteen) were to survive]].

* AllYourPowersCombined: The unique quirks wielded by Izuku's human fusions (referred to as "quirk mutations") are all variations of their parent-component's quirks, making them more flexible and powerful. Such mutations include:

** Izuchako (Ochako Uraraka): "Gravity Manipulation." A level of gravity control both on herself and objects around her much more powerful that Ochako's to the point of it being easy to confuse it for telekinesis. Nausea weakness is still present.

* FireForgedFriends: Literally. Every time Izuku fuses with someone, he fosters a familiarity with them that remains after they de-fuse. [[spoiler:This also applies to multi-person fusions, for ''all'' the component partners]].
** When Moku de-fused, Momo started addressing Izuku by his first name instead of his last name like she previously had at the start of the "Heroes vs. Villains" exercise.
** [[spoiler:After Tsuzuru de-fused, Minoru and Tsuyu not only started addressing Izuku by his first name, but also each other by first names. Their interactions were also a lot more casual, bordering on VitriolicBestBuds]].

** Sato is the one who escapes from the USJ attack to warn the faculty instead of Iida, which means that help takes longer to arrive since Sato doesn't have Iida's SuperSpeed.

*** During the USJ arc, [[spoiler:Izuku finds he can create three-person fusions, which he does with Minoru and Tsuyu]].

* AlmightyJanitor: According to All Might, Nana Shimura, despite being the strongest hero of her era, never came close to breaking the top ''one hundred'' in hero rankings. Before All Might, none of the One For All users were ever close to high in the rankings since being the best was trivial compared to protecting others. All Might himself only bothered with becoming the Number One hero because it better allowed him to spread hope to the common citizen, reducing crime rates and thus, theoretically, saving even ''more'' people.

* AlmightyJanitor: According to All Might, Nana Shimura, despite being the strongest hero of her era, never came close to breaking the top ''one hundred'' in hero rankings. Before All Might, none of the One For All users were ever close to high in the rankings since being the best was trivial compared to protecting others.

* LogicalWeakness: When using Fusion on inanimate materials, Izuku is only able to fully transform himself if has [[ElementalBaggage enough material to do so]], and he's only as tough as said materials.

* EurekaMoment: Deku when he realizes that he can use his Fusion Quirk to merge with something tough enough to increase the durability of his bones, such that he can withstand using One For All without breaking them. He wonders whether he should be feeling smart for thinking of it or dumb for not doing so earlier.

* EmbarrasingNickname: Bakugo barely tolerates Izuku calling him "Kacchan", but he absolutely hates when everybody else starts doing it.

!!Tropes:
* AdaptationalNiceGuy: Bakugo is much nicer in this fic, as a result of Izuku developing a quirk when they were kids and others ''still'' bullying him for it, Bakugo became Izuku's OnlyFriend for a long time. While he can still be a {{jerkass}} in the present, he comes across more as a JerkWithAHeartOfGold to Izuku and, later, Ochako.

** Aizawa ''probably'' shouldn't have let the girl whose power is "Turns off gravity," go first in the ball throw test. They never get that ball back.
** Todoroki himself just froze the entire building without thinking of a backup plan if the other team had a way to bypass this despite Iida trying to convince him to come up with one before they started.

* DoesNotKnowHisOwnStrength: What happens when [[spoiler: Tsuzuru]] jumps while combining Tsuyu's [[InASingleBound frog legs]] with One For All - the result sends her flying so high she [[WatchOutForThatTree crashes]] into USJ's dome ceiling.
* DramaPreservingHandicap: Using Fusion to boost Izuku's durability means that using One For All won't destroy his arms every time he uses it, so that's a plus. However, it seems to also limit its power somewhat, keeping him from just using a MegatonPunch with every blow. He can still launch extremely powerful blows, what would normally be considered a MegatonPunch, but it's not the OneHitKO that it normally is.
* DrawAggro: This is Bakugou and Uraraka's strategy in the Heroes vs. Villains exercise: Bakugou assaults the villains from the front and gets them to focus on him, Uraraka sneaks in through a window and captures the weapon. Interestingly enough, in canon that's what Midoriya and Uraraka did ''against'' Bakugou, exploiting his LeeroyJenkins tendencies.

* EmergencyTransformation: Non-permanent variant - [[spoiler: Izoru, Izuku and Minoru's Fusion, fusing ''again'' with Tsuyu to save her from Shigaraki's [[MakeThemRot touch]]]].

*** Likewise, Ochako and Bakugou have their costumes altered. Ochako's suit is more form-fitting to allow for easier movement with her Quirk, and Bakugou has several smaller bomb tanks on his gauntlets instead of one big one.

*** During the USJ arc, [[spoiler: Izuku finds he can create three-person fusions, which he does with Minoru and Tsuyu]].

** Fusions with Momo and Mina are both girls as well, leading Bakugou to declare that the gender of his Human Fusion partner determines the fusion's gender, so any time he fuses with a girl will result in this. [[spoiler: Three-person fusions are more problematic, since while Tsuzuru (Izuku, Tsuyu, Minoru) is a girl, Katzuchako (Katsuki, Izuku, Ochako) is a boy.]]

** [[spoiler: Three-person fusions are extremely strong, but apparently burn through the allotted time ''much'' faster than normal. Tsuzuru's components split well before the normal limit, and they're heavily exhausted]].

* JumpedAtTheCall: Mina is actually really unexpected for Izuku, as she's the first person to actually volunteer to fuse with him. Bakugou fused with Izuku first on accident, Uraraka was fused with to save her from the zero-pointer, and Momo did accept, but Izuku offered first.

** Aizawa's quirk nullfies other people's quirks. When he uses it on a fusion, the fusion splits apart instantly.

* MentalFusion: A fusion merges personality traits from both Izuku and whoever he fuses with. In Izuku's case, this means that the majority of the fusions have a tendency to MotorMouth (whether boastfully like Katsuki, outgoingly like Ochako, or [[GenkiGirl exuberantly]] like Mina) and call Katsuki "Kacchan".

* TheRival: Bakugou has two this time around: Izuku as the holder of One For All and the person he strives to keep ahead of, and Ochako for edging him out as the highest scorer in the U.A. entrance exam (since she was given Izuchako's Rescue Points alongside Izuku).

* StupidSacrifice: Discussed regarding damage taken by Izuku's fusions upon unfusing, specifically when Izuku took all the damage sustained by Izuchako onto himself instead of splitting it like he usually does with Katsuki, leaving him incapacitated with a broken arm and nausea while Ochako remained uninjured. All Might says that while his choice is [[ChronicHeroSyndrome noble]], it is also unwise in some cases, such as in the middle of a battle where it's a better choice to have two injured but still active heroes than one uninjured hero having to protect an incapacitated one.

** During the first Hero Class and the Hero vs. Villain exercise, Izuku thinks he'll be okay as long as he is on a team with Bakugou or Ochako who he can fuse with without any drama. Guess who's not only ''not'' on his team, but paired up with one another?

* WhatTheHellHero: Katsuki really gets on Izuku's case for taking all the damage that Izuchako took when she used One For All onto himself, leaving Ochako completely unharmed when they unfused and Izuku with the busted arm and even nausea from Ochako's Quirk. All Might shares the sentiment, pointing out that while the idea was noble, doing the same in a real-life combat scenario could lead to him being completely incapacitated and force his teammate to defend him.