They worked towards a goal

Mind:

Aaron's mind was sent into the past body of a genius, three years before the zombie apocalypse. This person's name is Isaac Moores; in his world, he created their version of Amazon, Google, and Apple, using that capital to fund construction boons in previously overlooked places, like underwater cities or island nations reduced to tourism industries. Isaac used his intel networks to steal shipments of trafficked humans and operate an illegal smuggling ring, allowing him to bring up the necessary numbers in these countries of **** workers to create cheap businesses and buildings that were up to code. Because of his actions, his workers were paid less, but still great wages for these countries, making him seem like a benevolent genius, which got him nominated for humanitarian awards.

He also had projects working to create devices that could rewrite a person's genes using simple writing prompts, as well as an AI development program. His goals for these were a world where people didn't need to work, a world where people would be safe from sickness or harm.

When Isaac got Aaron's mind, since it was Isaac's body, Aaron's mind was reduced to just its memories. These memories were crystal clear to Aaron, and he thought of going to Aaron for clarity, but he assumed Aaron's wish had been botched, giving Isaac this miracle. With this chance, Isaac thought he could be the thing that saves humanity. With his analytical genius, Isaac knew he couldn't just announce the apocalypse and trust these memories implicitly, but he also knew there was too much humanity and data from Aaron for these memories to just be some delusion. As such, Aaron decided he could take the risk due to his immense capital, using his social media accounts to release suspicious posts that went against the officialness of his posts. One such example was two linked posts, one showing off game media and shit relating to apocalypse stories, such as Fallout. These images didn't give any explanation of how they seemed to tie together in any other way other than nuclear armageddon. As for the other post tied to this one, it was about Isaac creating several large-scale bunkers or doubling efforts in underwater construction. Isaac was diverting a significant amount of funding to these projects, offering the chance for people to become sponsors. There were other things, like intentionally leaked documents detailing the hiring and relocation of skilled veteran employees in jobs like agriculture, police work, and many other professions, or those with such skills. Isaac even hired those with experience dealing with attackers or who've participated in various combat situations. His support structure was massive, so building large bunkers and underwater cities was heralding, given the time span, but it was doable.

When the press and government forces came asking for details, Isaac made it intentionally seem like he had something to hide, hopefully getting others to prepare on their own.

However, despite everything Isaac was doing with his construction projects that built bunkers and small fortresses to guard them, as well as underwater settlements, his bigger goals/aims were in his passion projects regarding AI and gene editing. Using Aaron's memories, Isaac already had part of the vaccine and cell structure of the zombie virus that Isaac saw glimpses of, so, at the very least, a vaccine was possible, even without the gathering of geniuses. Yet, just in case, Isaac got great intellects and talents from various scientific fields, whether they were besmirched or not. Isaac informed this select group of his knowledge, showed them what he was working on, and had them join his team. Since they didn't have the full cell structure or cure, they couldn't replicate either without at least having one. Thus, the team prepared to gain these samples when shit goes to hell, but mainly chose to focus on mastering genetic manipulation, creating a concoction that would spread throughout the atmosphere using their branches. When the apocalypse came, their concoction is supposed to use the data of the zombie virus uploaded into their systems to create a synthetic copy that the concoction would adapt to before releasing the cure. Since it is supposed to act like a cold for momentary immunity, the vaccine would vanish eventually, but it would buy enough time for Isaac to roll out a permanent vaccine, and hopefully lock the vaccine into a traditional zombie style.

On another genetic note, Isaac seized the experimental formula that turned Aaron into a fucked mutant; Isaac ensured his boys experimented and improved that serum, hastening its research and securing a facility where it could be worked on after.

Though Isaac devoted so much time to preserving mankind, he continued his AI project, collecting those talented in engineering to hasten the creation of a mechanical body and mechs. Isaac planned to use an army of these metal men to handle any outbreaks and become a dominant **** that would rebuild the world should things fall to shit.

Also, Isaac donated a lot to space organisations, claiming Mars rights as he tried to rush a fleet of rockets into space to colonise the Moon, or just sit in orbit under the pretext of a massive space cleanup, and an early attempt at space habitation. If all else failed, Isaac hoped space could keep a bastion of mankind. Isaac planned to initially send up early rockets with recyclable supplies, such as tons of dirt and various equipment. Even the rockets were designed to crash onto other celestial objects and be scrapped in a way that would bring more parts.

On a last note, Isaac decided to help out Aaron, giving him a LOOOOOOOOTTTTT of money, his way of repaying Aaron without having to look out for the kid.

Body:

Aaron's body was sent into a time before magic in this world vanished, leaving a few hidden clans in the modern era to practice different kinds of mystical arts created or left after the disappearance of mana. In this era, Aaron's life was saved, and the only thing that limited this age of men was their imagination; all the while, people didn't know their magic constructs would disappear with them, leaving these earth-bound to die without realising the dreams of space or advancements that might secure their progress.

Spells, superpowers, sorcery, mystical martial arts, cultivation, and many other forms of magic died, leaving few lucky bastards to carry the wisps of magic on with them.

They acted like they were one with the universe or nature, like immortals from Eastern mythos, or druids from various mythologies. There was no sign of deterioration, no example of a drought or loss, only what is and what will remain to be as is. That's their view on life. Aaron was the only one who knew otherwise, and he was the only one with an understanding of other things, for these people's minds were dull in the face of his own. Aaron used tricks, extortion, magic, and many other ways of gathering people to his cause as he restored his form, using the serum inside of himself to grow his strength, becoming like a cultivator from stories.

Soon, when magic disappeared from the world suddenly, Aaron and his merry band grasped all the magic they could, maintaining their home on Mars, a planet lacking magic from the very beginning. Aaron saw it as a perfect place to test themselves, adapting before magic left their land and became a limited source expressed in mild forms. It was tragic, but using his agents who had already adapted/trained on Mars' barren environment, Aaron and his people watched as the end of this era came. The Immortal Realm and its immortals fell from the sky, the clouds turned from cushions to water molecules, sky islands caused the world to shake when they landed, kingdoms fell apart like mounds of dust to the wind, and there were so many deaths. Anything magical disappeared or died, leaving creatures with non-magical bodies as the only lifeforms, and nothing for people to remember their past, getting distorted over generations that didn't know how to maintain a true record.

Aaron was certain he wouldn't distort the time stream, that he wouldn't kill his future self. How could he? With so many dead or hiding in fear, those he took were probably part of the hundreds of millions dancing in the skies. The only good thing for the world was that those who died as a result of magic's vanishing were able to pacify the land. Bodies turned into trees, structures made of magic vanished, and the islands that crashed smoothed into mountains. Meanwhile, any destruction of the ground was filled with rock and minerals, and ecosystems miraculously survived without the magical animals or trees.

Aaron was certain he did not need to worry about the future. With assurance in hand, Aaron ordered his people to stay hidden from the surface, to store magic, rather than using all of it for each generation. This way, Aaron's people could occasionally commune with other mystical communities, staying out of history as they recorded the secrets of each clan, building their power till the day came that Aaron's soul would arrive, drawing Aaron's body to it. In the meantime, Aaron's body called itself Form and trained his cultivation magic, continuously enhancing the serum to be part of his dantian, giving up traditional cultivation now that the world had lost its vitality, and instead training his form, rather than cultivation power.

Soul:

Getting sent into his younger body, Aaron's older soul merged with his younger ones, giving him perfect recall over his past soul's life, memories that even he forgot, including suckling on the teat of his momma. Since he was still a baby at this point, this helped Aaron prepare for the shock of feeding that was about to happen. But it wasn't like that was important; Aaron's brain was too young to handle all these complex thoughts and memories, so, soon after feeding, his future mind went ****, making him a blank baby with one instinct in mind: Prepare.

Aaron then spent the rest of his life preparing for something he wasn't sure why he was so dedicated to preparing against, believing he was simply a fanatic for zombie apocalypse stories. Still, Aaron continued his training, training in each martial art to he was deemed a master. Boxing, karate, jiujitsu, archery, CQC, guns, tanks, geography, survival, biology, engineering, etc. Aaron trained in everything, he conditioned himself to keep up with current events, and he always had stuff set up wherever he went. Aaron was just waiting for that magical something, knowing he had done everything and more for that fated moment.

In preparation for the apocalypse, Aaron even fought in war zones as an unsanctioned liberator, became independent at an early age to adopt prospects using a fake ID, and slowly worked himself up to more and more dangerous foes for practical experience. Aaron's fought people, wolves, lions, bears, and a lot of other bastards, spending his entire life as a weapon of destruction.