Just An Experiment To You - Venti

Izuku Midoriya, born quirkless, was an experiment for ten years. He was kidnapped at age six, and has lived in a quirk experimentation lab ever since.

The heroes hear about the lab. When they go charging in, they don't expect to find the sixteen year old there.

When one pro hero by the name of Eraserhead decides to adopt the child, he has no idea the challenges he'll face.