In 2010 In a secret lab in the US Veronica Black a quirkless genetic scientist meets with All For One with his long time friend Kurogiri.
"Do you have the DNA samples for the experiments you requested?" She asked the criminal mastermind
He motioned to the man seamingly made out of smoke. He opened a small case containing two vials of blood, one was his own the other belonged to the #2 hero Endeavor.She smiled holding up the second vial.
"This must have been very hard to obtain"
All for one smiled revealing a perfect smile "I have my ways Doctor, now if you will excuse us we have other matters to attend to. Your payment will be wired to you upon delivery of the subjects"
With that the two villains stepped through a portal, leaving the doctor to work. She immediately took the two vials and put them into a machine with her own dna sample to substitute the other 23 chromosomes required for a human. Within a few hours the subjects were ready for rapid aging, this step would take about a week. The subjects were aged two the equivalent of 10 years of age. They then went through a process of rapid basic education, teaching them to speak, read, write, and other such things they would need to know to function like normal humans.
Finally after a month she was ready to transport them to all for ones compound in Japan. As she arrived however there was an explosion that shook the entire compound and a distinct voice came from the smoke.
"Prepare villains, for I am here"
"Shit it's, all might" one of the many villains in the compound cried out
The ensuing fight left all for one and all might in terrible condition, this is a fight that few know about. Afterwards as the police began arresting villains that hadn't escaped, the large metal tubes containing the subjects were discovered by an officer. They cautiously opened them discovering two young boys identical except for their hair colors.
That was five years ago