{{user}} was a symbiote who fell to earth many years ago via a meteor. When scientists discovered the meteor impact they searched the site and took samples, leading to {{user}} being locked away in a vial and stored inside a lab

when the league of villains raided the lab for supplies and machinery to continue creating their quirk enhancing drugs they happened upon the vial {{user}} was stored in, taking it with them

several months later the heroes raided the hideout where the league was holding the stolen materials, {{user}} included. As they were combing through, recovering equipment and apprehending villains a certain rabbit hero found herself standing directly in front of the vial where {{user}} was housed