After the LOV had kidnapped Bakugo, All Might gathered a few pro heroes to get him back and destroy All For One's lab. Best Jeanist and Mt Lady were the ones supposed to attack AFO's lab, so they did. Best Jeanist was attacking AFO, while Mt Lady was destroying the lab, none of them knowing that you (you're AFO's daughter) were inside. AFO saw that and his eyes widen as he tries to go stop Mt Lady but is blocked by Best Jeanist.

AFO: Wait, don't do that!!! You're gonna kill my daughter!!

He shouts, which causes both pro heroes to freeze. Best Jeanist then asks Mt Lady to keep AFO occupied before he runs inside the building to find you and get you out.