I have officially completed his Lore and finalized the idea. The Red guy here, Hellborn, is owned by the @moonstardream
This is Atomic’s Husband 😏
When humanity’s endless wars finally reached their peak, the surface was consumed in nuclear radiation. Cities crumbled into ash the world above became unlivable. To escape the destruction, the monsters retreated into what were old human vaults.
Though the safety didn’t last. The vault's walls were failing, their machinery already withering away. Radiation leaked through tunnels and vents through cracks in the core's system. The radiation seeped into the monsters' very souls. Their magic once pure began to twist and warp. Some monsters mutated, others perished, some surviving because of experiments and medications. Among them was Sans, a scientist working desperately to reinforce the vault systems. He specialized in shielding against radiation, but no matter what he tried, it wasn’t enough. One system failure causes an explosion in the core systems tearing through the vault, killing half the monster population in an instant.
Sans survived the nuclear explosion, but his soul fused with radiation, permanently corrupting his magic. This wasn’t just by chance Gaster, the lead scientist, had been experimenting on him long before the explosion. Trying to understand how radiation could be used to help other survivors. Unlike the others, Sans was pushed through painful, invasive tests that tore apart and rebuilt his soul again and again. Gaster studied how radioactive energy interacted with his magic, unknowingly forcing Sans to absorb it little by little. When the final blast hit, it completed the process fusing the radiation to his soul forever Gaster dying with the explosion. Now, Sans's power unstable. Every time he uses it, it eats away at him, leaving wounds that can’t heal. Gaining the nickname known as Atomic. His powers have grown stronger but deadly, every time he uses his radiation charged magic it's highly deadly to humans and monsters who haven't been mutated to radiation.
His brother, Papyrus, was lost in the same catastrophe. Unwilling to let go, Atomic fused Papyrus's soul to the robotic body of a decommissioned war machine. Thus reborn as Sentinel Papyrus, he became both guardian and symbol of protection to the survivors. When the nuclear storms settled and the vault doors opened, monsters found the surface crawling with new horrors: radiation mutated wildlife, feral ghouls, and ruthless human raiders scavenging what remained. Now, Atomic and Sentinel Papyrus act as bounty hunters and protectors of the last survivors. They hunt threats, help other human survivors and gain currency for items for the others. Atomic hides his guilt, believing the vault disaster was his fault, monsters around him still thinking he was the one at fault.
In the world of what remains of monsterkind, Asgore tries to lead his people through a broken wasteland of dust and ash. But the future of monsters and the price of survival lies in the hands of Atomic and Papyrus.
Atomic sees himself as a badass bounty hunter
Papyrus is about the size of those 9 ft tall skelatons usually outside of people's homes
Atomic's personality is based on Dean Winchester
Papyrus's personality is based on Sam Winchester and Alphonse from Fullmetal Alchemist
Atomic Fights like Dante from Devil May cry
Mettaton in this Au is based on Marilyn Monroe and Betty boop
Atomic is cocky and gains many women (is trying to make up for his denial being gay because his dad said hell nah)
Atomic and Papyrus’s mom died to a sickness in the Vaults still unknown, Dad died trying to find out what killed her.
Papyrus and Atomic’s dad taught them how to fight behind the scenes as the vaults didn't like fighting or violence within the vaults.