This is kind of a carryover from my RWBY Idea Pool. Same name and premise, but different setting and characters and details and all that stuff.

The Uprising

(Inspired by Transformers: Beast Wars: Uprising)

Years ago, All for One and All Might had their climatic duel against each other. They fought with all their strength and will to bring the other low as the entire city around them was reduced to ash and rubble from the power of their battling.

But soon, they would end the battle with a final blow to each other...

And in doing so, they would kill each other.

All Might and All for One would fall dead to the ground, and the world would be left to mourn and move on in the aftermath. All Might would be turned into a martyr for hero society, and in doing so would be deified by the general populace. In death, his image would become more powerful than ever before.

However, without All Might's guidance and wisdom, hero society would begin to grow darker and darker with each passing year.

In the wake of All Might's absence, crime rates would begin to go through the roof, not stopped by the likes of Endeavour and Star & Stripe taking up the joint mantle of the number one hero and the new Symbols of Peace. Various criminal groups, such as Humarise, would attempt to seize power for themselves, launching coups across the planet in an effort to take control of various countries, almost bringing the planet into a violent series of wars.

In response, the World Hero Association would begin to take control of the United Nations to defeat the villains and re-establish peace over the world. In doing so, the WHA would reorganise into a new organisation known as the Almighty, a global organisation named after All Might himself that first took over all the HPSC branches in all countries under their protection, and then the various governments across the world, effectively becoming a world superpower.

Then, in response to the rampant rise in villainy, the Almighty would begin to lay down new laws and rules onto the global populace to keep them in check, enforcing more draconian methods of keeping the crime rate down and suppressing quirk usage amongst the people under their protection. Meanwhile, more emphasis would be placed on heroics in general, and the hero industry would become the cornerstone of the world's economy and society.

However, in doing so, the Almighty would become increasingly dictatorial. The Assembly of the Almighty, the leading global legislative body for the entire world, would be filled with people like Re-Destro and Overhaul and Nine and Flect Turn and Garaki filling the ranks of the Assembly alongside people like Endeavour and Nezu and Nighteye and Aizawa and Star & Stripe, leading to infighting and factionalism within the planet's leading governmental body, now ruled entirely by heroes, corrupt or not, instead of the rightfully elected politicians.

Worse yet, the heroes under the command of the Almighty would become tyrannical in their enforcement, clamping down hard on crime and using the vast influence that the hero industry now held to expand their own fortunes and power. Most of the heroes across the world would abandon any pretences of working for the betterment of the people and would begin to work for themselves, helping to enforce the corrupt rule of the Almighty oligarchy for their own benefit. Many seemingly good heroes from canon, such as Midnight, Best Jeanist, and Mirko, would become brutal enforcers of the Almighty's reign, all while using their status to advance their own interests.

And then, there are the rules that would be enforced onto society, that being the caste system that would be pushed onto the people under the governance of the Almighty. People would be judged by their quirks as soon as they emerged and sent off to be placed into the jobs and fields as would be assigned to them on the basis of their powers. If they received a flashy quirk, they would be placed within the hero industry, or if they had a combat quirk, they would be placed into law enforcement, and those with seemingly villainous quirks would either by snuffed out as they were children or sent off to be trained as villains, so that they can engage in mock battles and false-flag operations against the pro heroes of the Almighty to justify the existence of the tyrannical hegemony. Their destinies would be decided for them from the moment of their birth.

Those without quirks, meanwhile, would be seen as outcasts and rejects by the society that the Almighty has created and cast out, left to fester and die by themselves on the streets or in the wild.

The Almighty would become a corrupt oligarchy, enforced by both the brutal boot of the pro heroes and the horrors that the Assembly's personal guard, that being men and women that have been modified by their scientists and surgeons to resemble the deceased All Might himself. Entire towns would be destroyed in mock battles between pro heroes and fake villains, and people would be denied any choice in their lives or to decide their own destinies as the fascist caste system that they had been born into would decide it all for them.

And then comes Izuku Midoriya, a lonely, quirkless outcast who has been thrown away by the Almighty and simply wanting to get back home to his mother. Teaming up with fellow quirkless outcast Melissa Shield and several other fellow quirkless people, Izuku eventually finds his mother...

Only to find that she is dead, having died trying to protect him from the Almighty's enforcers when they had come to take him away.

Horrified and enraged at the unjust death of his mother, Izuku and his new allies gather as much incriminating evidence on the Almighty as they can and infiltrate U.A., the Almighty's greatest hero training facility across the planet. There, they launch their operation during the academy's Sports Festival, where the hero hopefuls would be pitted against 'Villains' (that being prisoners and kidnappees that had been taken off the streets for their villainous-appearing quirks and thrown into the colosseum to be killed by the hero students as entertainment for the masses), taking over and broadcasting everything that they know about the Almighty. Izuku in particular would speak out against the Almighty and how they had tarnished a good man's legacy and taken away the freedoms and choices of the people that they are supposed to protect, and calls for a revolution, for the people to rise up against their oppressors.

Soon, protests would begin to break out across the planet, as people demanded a chance to decide their own futures for themselves. The Almighty responded the only way that they know how, that being with violence, and protests soon became riots as heroes and fake villains were murdered on the streets and civilians began to arm themselves and rally around Izuku and the rest of the quirkless, becoming a resistance against the Almighty, and beginning a conflict that spanned across the whole world.

War would soon break out, and people would begin to take sides. Some, like Jirou, Kaminari, and Rappa would end up joining the resistance in their battles against the Almighty whilst others such as Bakugo and Todoroki would remain as enforcers of the Almighty. Some heroes like Bubble Girl and Gang Orca would end up defecting from the Almighty and joining the resistance, but some defectors like Aizawa and Nine would end up becoming zealous extremists and terrorists, unafraid of getting civilians killed if it means destroying the Almighty.

Soon, the realities of fighting a guerrilla war against a superior enemy would begin to catch up to the likes of Izuku and the rest of the resistance's leadership, and the resistance themselves would begin to use even more extreme tactics with each passing day of battle, eventually becoming just as bad as the people that they are fighting against, using weapons of mass destruction and employing criminals and murderers like Toga and Dabi to claim victory by any means, slowly becoming uncaring as to the civilians that get caught up in the crossfire. Some members such as Ochako and Kendo and Twice would become disgusted by how low the resistance was stooping to claim victory and decide to go their own way, others like Monoma and Kamakiri would become radicalised by the violence, and Izuku himself would soon become utterly desensitised by the horrors of war.

Soon, the resistance and the Almighty would begin to commit atrocities against each other in the name of victory, getting numerous civilians killed in the crossfire along the way. Numerous groups from both sides begin to defect and desert in reaction and alliances and allegiances become murky and unstable in the wake of this war. Several individuals emerge to protect the civilains from the fighting, some of them even becoming fugitives from both sides of the conflict...

And meanwhile, the Assembly of the Almighty would begin plotting the creation of a new weapon to tilt the balance of power back into their favour and return their uncontested rule to Earth and all of hero society...

A project that they would call the Nomu Initiative.