Idea: Izuku lives in a world where almost all women have quirks, and it's believed that All Might is a woman, but in fact, a man.

I wanted to take the cliche 'MHA world filled with powerful women, and quirkless men' plot, and give it a different twist.

Izuku is the Doomguy/Doom Slayer.

Izuku gets One For All.

Some parallels to canon.

Izuku is a willing mute.

Doom dimension starts invading after the Icon of Sin is beaten but before the UA entrance exam. I won't take the Ancient Gods DLC into account for this story, but it doesn't mean I won't borrow ideas from it if I feel it fits.

UA is a university.

I will summarize the changes from the first MHA episode, instead of writing the same thing 95% of MHA story writers write.

Of the population of the world, instead of 20% of the world being men, let's say 10%, as 20% means the idea of 'Never seeing a male' is kinda dumb otherwise, as that would mean for every for women, there's one guy, or 4/5 women (80%) and 1/5 men (or 20%) to 9/10 women (90%) to men's 1/10 (or 10%) meaning one man per classroom lets say. So if say, if the human population is, let's say 8 billion (8,000,000,000) that means Seven Billion, Two hundred million (7,200,000,000) are women and eight hundred million (800,000,000) Men in this world.

Using this idea, let's say Japan's population is rounded up to one hundred thirty million (130,000,000) for simplicity in the math. Now, 90% of this number is Women, making it One hundred Seventeen million (117,000,000) in terms of population, while men would make up a small Thirteen million, (13,000,000) making them an actual rarity, vs the silly idea of Izuku being the only man all of Japan has seen, for some reason. It's not meant to mock at stories like Total Command and Doom: Slayer of Hope (Both fantastic stories, that in my opinion, kinda ignore the flaws of making a population of anything 20%, hell canon makes this mistake honestly.) which I love both of, but it is a plot hole when you think on the actual math and statistics of it. So in that sense, I want it to be more realistic of such a scenario, and to remove the story damaging (to me at least) problem of the 20% thing. I want to portray it more different than it is in both the anime and fanfiction, as I don't think most people really notice it.

Each classroom under the 20% would have at least one male, or one quirkless person, making it less reasonable that only like, Two people in a Major City would be surprised by such a fact of meeting up, as it would be reasonable to believe that they would stick together, vs whatever the fuck they do in canon.

The final bit, will this story be a Harem?

If it wasn't obvious, yes. But most have girls fall in love because of 'big man big' or something stupid, instead of more reasonable growth. Izuku is going to be oblivious, mostly because his last interaction with an actual female human, besides Olivia, was Eons ago. So it is reasonable to believe his social skills would degrade due to a lack of use, and his endless rage for the deaths of Demons, even with his ability to show some concern for humans and Daisy.

Firing the last shot needed, I watch the Icon of Sin tumble backwards, trying in vain to prevent it's defeat, as I run to it, and stab my blade into its brain, ending it's the ability to regenerate, and stopping it from dragging this universe into Hell. I then break the blade off from the hilt and jump off its head, to avoid joining it in it's tumbling down motion.

Turning around slightly, I grin slightly, watch the massive, monstrous corpse of the Icon of Sin slowly slide down the building, unable to harm anyone again, so long as the blade remains in its brain.

I start to hear the cheering of the people of this Earth, celebrating the end of the demonic invasion caused by power-hungry fools, arrogance, and the strange belief of the Demons being allies to them.

It doesn't matter though, with Hell weakened to a degree where it can't raise an army to truly invade a realm for a good while, I silently sigh, walking through the portal that formed right behind me, heading back to my Fortress of Doom.

Stepping back on the fortress, Hayden's voice greets me. "Welcome back Slayer. While I have news for you, you should have your blade repaired again, as I have news that may interest you."

I just grunt out a response, setting the portal's destination to Taras Nabad, to quickly repair my sword, as I am slightly curious about what Hayden has to say.

Arriving in Taras Nabad, I walk through its halls, and crumbled buildings, slaying any straggler demons along the way, and repair my Crucible, should I ever need it, and picking up ammo for the BFG and Unmaker, to have extra should I ever need it against a horde of Demons.

I see a Hell knight walking around an entrance, and quickly kill it with a few shots from the Super Shotgun, as I watch its body disintegrate as the blood pools around the floor, passing by the scent of ash and blood filling the air, thanks to the fact that I slaughtered more demons on my path to fix my sword.

Eventually, I get another token for the Crucible and reach the pool of Hell Energy, to fix my blade. Dipping the sword's hilt just enough into the pool, where the blade reforms, and I have the portal set up, and I get ready to leave when I hear the roar of a Baron of Hell.

I turn around, readying The Ballista with the Arbalest mod, and fire a shot at the Baron, who nearly avoids it, and roars at me, rushing up to me, but I move as well, pulling out the Super Shotgun, and blasting large chunks of its armor off, revealing its lava-like blood, before I fire another shot, breaking the armor enough for me to rush to it, and slice it's head off with the Doom Blade, felling and ending its life for good.

The head rolls through the portal, much to my annoyance, lava blood is a pain to clean from the floors after all. I jump through the portal, to find out what Hayden wants. Better be a new weapon that can kill more demons faster or an upgrade for one of my weapons.

I grunt in annoyance, seeing the head of the Baron of Hells head on the ground, before it turns to ash, at least it will be easier to clean up. One thing less to deal with.

"Ah, welcome back Slayer. I will get straight to the point, which I am sure you would be glad of. With the help of Vega, we were able to find a way to have you return to your home dimension. Using the runes used to seal you as a base, and examining the runes used to make Gore Nests, Vega and I were able to create a portal that could lead you home." His mechanical voice echoes throughout the base.

I stew on it for a few seconds. A way back home? That's bigger than how I got here.

But do I want to go back?

While I have saved this universe, the Demons will never stop. They are rage, brutal without mercy, but I am worse, and I swore to Rip and Tear until it is done.

At the same time, I can't help but wonder, what has changed since I left, if mom is still even alive, and not dead or a pile of dust.

How do I know the Demons can't access it? I mean, I ran into an Imp, who unknowingly helped make me into Hell's worst nightmare.

I should go, in case if Demons are running amok there, and it's not because of any blood loyalty to it. Should they be supporting the Demons like UAC had, they will find what it means to face against the Hell Walker.

I grunt a confirmation to Hayden. "I figured you would wish to go, Slayer. Take what you can, as the portals one way currently. I am looking to make it two way, but it will take a while." Hayden's mechanical voice says, having what I can tell is annoyance at the fact he hasn't figured it out yet cut through his normally neutral tone of voice.

I grunt an acknowledgment and begin collecting the stuff I will taking with.

Like the Portrait of me and Daisy, enough ammo to last me three sessions in Hell, and the journal that I have had since I was mistakenly brought to Hell. I look at the front of the journal and see something I haven't thought of in Eons.

The ideas behind the journal, before I became what I am now. It's scorch marks, while faded and dried, remains from when Katsumi blew it up, literally.

Hero Analysis for the future.

I flick through it, memories slowly coming back, back when I was still innocent, weak yet strong with determination, and when I wasn't something akin to a rage machine.

Heh, it's interesting to see-

Wait, I remember this. The day I meet All Might and found out more than I could have guessed at the time.

The day at the time was any other day. Going to school, have the train delayed due to a villain attack, make notes on the latest hero, MT Lady, if I remember correctly, go to school and get laughed at for wanting to be a hero.

I got used to that, though after class, Katsumi took it way too far, telling me in so many words to jump off a building. That went too far, so in retaliation, I punched her in the face, and ran off, after grabbing my journal from becoming fish food by the koi.

I eventually ran underneath a bridge, just wanting to go back home, and that's when I was attacked by a slime villain, which at the time I couldn't defend against.

The HE appeared. All Might. At the time, like all most all of Japan, and possibly the world, I was under the impression that All Might was a female, not a male do to the 'Only women have quirks' mentality. He rescued me, and I foolishly at the time, jumped onto his leg due to my wish for answers from my idol at the time.

That's also how I found out about him being male, his injury, and his time limit.

Then he told me I couldn't be a hero, due to me being quirkless. That I should become something safer, like a detective or something among the lines.

Looking at it now, it's funny that I went from a weak nobody, jacked-up rage machine hungry for the deaths of all demons, becoming much stronger than I was Eons ago.

Well, after having my dreams crushed, and hearing a nearby explosion which I rushed to, and found Katsumi trapped by the slime villain from earlier.

I rushed in, distracted the villain, and tried to save Katsumi, only for it to fail, and All Might to jump in, and defeat it.

I was scolded by the heroes, and as I walked home, I noticed something off and encountered my first Demon, an Imp.

It saw me, and it attacked me, as I dropped my phone on the ground. After a minute of struggling and I was pulled through a portal.

The rest is history, I fought the armies of hell for eons, and here I am now, about to come full circle. A portal back to my birth dimension. Should I be excited? Possibly, but from what I remember of it, it's not going to be fun.

I finish putting up my figures, both from my awakening on Mars and here, I wish I found out who made them, and the Vinyl records I collected over time.

After packing up the last of my things, and putting my computer, so overpowered that it could run practically anything, up in a quantum storage device, I head back to the main room of the Fortress.

I make a loud grunt sound, to catch Hayden's attention.

"I see you have finished Slayer. I have finished configuring the portal to take us to the dimension. I will now download myself into your suit." Hayden says before my suit lets me know that he is in my suit's data storage.

I take one last look around the Fortress before I press the button to activate the portal.

Three months since he disappeared. Three months of my failure.

I should have realized that I should have approached him sooner before he disappeared.

I was delayed by the reporters longer than I liked, and when I went to meet up with him, all I found was a phone with three missed calls and a pool of blood that wasn't his, thankfully. Even then, it doesn't make it easier to believe. I wanted to make him my successor if I am, to be honest. If I do find him, I will make sure to apologize and make the offer to him.

Hopefully, he accepts and isn't traumatized by his experiences. If he was, I could never forgive myself for the failure. It would be especially worse if he was used for sexual pleasure, which while unsurprising, is sickening at the idea of it even happening.

I just hope young Midoriya is okay. One of my greatest regrets currently is treating him poorly, yet I wouldn't do anything until he, a man and quirkless, ran to save the explosive lady, knowing full well he could have died.

That day, he should more heroism than half the heroes today, and me. I talked a big talk, and it took him to make me walk said talk.

I turn my TV on and sigh, I am currently off the clock with an hour to spare of my time, I might as well and-

What the hell? Oh, SHIT!

I quickly buff up, and barge out of my room, to head to the nearest hospital, as it's under attack by unknown forces, monsters that have killed most of the patients, and a few local heroes already.

I quickly arrive at the hospital, to see what I was afraid of, rivers of blood, and bodies of the monsters and heroes on the ground, while the remaining heroes are still holding out, it's clear they need help.

"Have no fear, for I am here!" I announce loudly, throwing a punch to one of the monsters, at the orange bodied monster with spikes protruding from it's back, causing it to blow up into a multitude of chucks of body parts. Well, at least I know they aren't human, or of this world, based on the fact that the bodies I arrived at, and the one I just killed, turned into ash.

Suddenly, a massive fat one, wielding two arm cannons jumps from a nearby roof, and roars at me, possibly because of indigestion based on its size.

Seriously, the monster looks like it weighs a ton. Regardless, I throw a 25% power punch at it, destroying it easily. A few more monsters pop up, more of the little monsters, another two fat ones, and one that happens to be a big, ugly, tall monster, gray with a magma like color coming from underneath it, and two blade-like protrusions coming from its arms.

The monster looks tough, so I throw a 25% punch at it, killing the other monsters easily, and only causing it to be thrown back a bit, losing chunks of its armor, I think. I know for sure more of that magma coloring is showing, so I throw another punch, a 50% punch, causing it to be thrown back farther, disoriented as I quickly throw another punch, making its head explode in a shower of blood. Lovely, now it's going to take a while to get the blood out. I turn around, to see two more of those big guys coming at me, and as I get ready to fight them, a green portal pops up in front of me, having a futuristic armored warrior walking out of it, holding what looks like a shotgun with a strange hook on the bottom of the front barrels.

The monsters, seeing him, I can easily tell the warrior is a male, begin growling, rage visible in the monster's eyes at the sight of the man.

Stepping out of the portal, the first thing I see is two Barons of Hell. Great, they already are trying to take this world.

"Of all the places to end up, we land in Japan. Well, since there seems to be the welcoming committee here, go nuts Slayer." Hayden mechanical voice says, as I pull out my Super Shotgun, and use the meat hook to grapple to it, and fire a shot in the baron's face, causing parts of its armor to fly off, revealing it's magma coloring blood to the world before I slice it's head off with my blade, as a geyser of blood shoots into the air from the stump where it's head once rested.

I notice the other Baron is in combat with... All Might?

"SMASH!" All Might shouts, causing the Baron to stumble backwards from the force of the punch, shredding off its body armor, and causing a horn of it's to break off. He then finishes the Baron off, with another punch, causing the demon to become nothing but a pile of gib meat and blood.

Honestly, I didn't think I would see All Might again, whether is the one from my birth dimension, or from an alternate reality. He finishes cleaning the blood off of him and looks right at me.

"Young man, I would ask if you were insane or suicidal, but something tells me you aren't from this world, or time area, based on your armor. Regardless, who are you?" All Might asks, but I just ignore him at the moment, heading towards the center point of the invasion, the hospital, and I note the fallen heroes and almost 95% of the civilian bodies are women. So far, the evidence does point to this being my birth dimension, but I have my doubts still. I note that he is still following me, trying to get my attention.

Regardless, I find the Gore Nest, the source of the invasion, and rip its heart out, and ready up for a fight. A full minute passes, and nothing appears, how strange. Every single time I destroyed a Gore Nest, demons would pop up for killing, but this time, none came. That's very strange and worrying. They don't usually just abandon an attack that easily, if at all. They usually continue until either everything is dead, or they are dead. For them to just not appear, is a cause for alarm.

I turn around, to see All Might chest at eye level, arms crossed with a look of annoyance, and a bit of confusion. "Young Man, I don't know what you are after, but you are coming me. Take off your helmet, if you can live without it, for identification purposes." All Might says, giving me a stern look.

"Forgive the Slayer. I am unsure if he has taken an oath of silence, or has forgotten how to speak, or if his vocal cords have degraded from lack of use, so he doesn't speak. I am Samuel Hayden, head researcher of the UAC corporation before it was overtaken by cultists." Haydens voice says. I grunt in irritation at Hayden, though I know he doesn't know I can talk, I just have no reason to.

Though, I do think about the idea of removing my helmet. On one hand, I could refuse, but that would lead to a fight with a man who has been weakening lately, thus causing more harm than necessary to my once idol, and while I am sure I could win in a fight against him, I have no reason to fight him, it still would cause more harm than good.

On the other hand, if I take my helmet off, I can see his face of shock when he realizes who I am, and maybe see my mother again. Been eons since I have seen her, assuming she is still alive, and I don't remember the way home. It would also avoid a needless confrontation with All Might, and I don't want innocents to get harmed because I refused to take my helmet off.

I give a grunting sigh, and slowly remove the claps around my helmet, and take it off, looking All Might straight in the eye.

I can't believe it. It's been three months, but here he is, right in front of me. Izuku Midoriya, the fanboy.

"I-Izuku Midoriya!? Where have you been!" I ask, floored at this being Midoriya. I am glad to see him alive, but hell it's hard to believe he was that scrawny kid three months ago. Now he looks like me in terms of muscles, and the look in his eyes hides his rage, though not at me. What his rage is aimed at, I am unsure of, unless it's at those attacking monsters.

Izuku just grunts at me. "Izuku, I am going to ask you to come with me to the nearest police station. For security reasons and safety, I will be confiscating your weapons." I say, trying to keep the excitement out of my voice. I am so glad to see him again, even if the situation is less than desirable. Though, it's infinitely better than what I could have expected the potential reintroduction could have been.

He just grunts again, though the grunt seems slightly annoyed. I realize I have to be careful here, less this could go poorly. "I don't know what you have gone through young Midoriya, but it's a safety reason for us, that we confiscate the weapons, for now. You will have them back, once we are sure that you aren't a threat to us." I say gently, trying to keep the situation from escalating.

He just grunts again, but he slowly, as if he was holding a child, hands me his Shotgun with a strange hook on it. I guess that he has seen so much, that it's hard for him to let go of it for long. "Now, I just need you to write out the phone number of your mother." I gently say, handing him a piece of paper and a pen.

He just stares at me and the paper, as if he is unsure of what to say or do. But then the mechanical voice of Hayden comes through his helmets speakers. "There is a very high chance he doesn't remember it, All Might. It has been Eons since he thought on it, maybe your police station will have a record on his mother, and by extension, her phone number." Hayden says, though Izuku lets out an annoyed grunt at Hayden, I think, and writes something down on the paper, then hands it back to me.

I take the piece of paper back from Izuku, who seems to just be staring at me now, but the look is less of a rage-filled one, and more like his old self, but far more tempered, and a bit joyful. At least that part of him remains, which should make the question easier to ask when the time comes to offer it.

So, this is something I did. I made a crossover of Doom and MHA, something I had the idea of, and borrowed concepts from two far better stories than mine, and here it is.

This chapter is short, mostly because it was meant to be the introduction to the story, and a test for if I could write a Doom-style of combat, and I think I did decent with it. I hope you like this story, a bit more unique than my what feels like Two Thousand LOZ crossover stories, as it's in two franchises that happens to be different. I wanted to try a different style of writing, and I hope you guys liked it.

Also, Harem choices are undecided.

Happy late New Year, and lets hope 2021 isn't shit like 2020.

EDIT: Just some spelling mistakes, and a fixed a few wording choices and placements.