(85 years ago) Year 2079-
Agatha spent a normal life, as normal as Neo Argos can offer. She grew up without her father Dr Nathaniel, but he had left behind so much fortune for her and her mother Isabelle that his absence did not affect them at all. Agatha was able to graduate from the Atlanta University, the most prestigious university in the country. She fell in love with a man named Kojiro Arima.
On the night of her eighteenth birthday, she was bitten by a lesser Calamity, and ended up in the hospital. Although she was diagnosed to not have sustained any pathogens, the incident left her with deep trauma.
The Calamity that bit her was actually her father Dr Nathaniel. He intended on merging with her body so as to make progress in his grand plan. But her body was not compatible.
Agatha went on to study for masters in risk analysis and management. She married Tezuka and had a boy whom they christened Iori Arima.
Meanwhile Dr Nathaniel, in his Calamity form along with his vamp partner Samuel tried their best to make an antidote for turning the calamities and vamps normal again but nothing seemed to work. The presence of a compatible person from Nathaniel's lineage, who he would merge with along with making him consume the blood of Samuel who was the first vamp and had some of the enhanced viral fluid injected into him, was necessary.
Due to the viral fluid inside Dr Nathaniel and Samuel, their ageing was somehow stopped. Which meant that they could not have died unless they sustained a major injury. On top of that they had the regeneration of a calamity and a vamp, which meant that unless the heart or the brain sustained a major damage, they were able heal quickly. Even regenerating cut off limbs in a jiffy.