For as long as you can remember, you were in that lab. A horrible place where they experiment quirks on children. One day after your daily little experiment, someone get pushed in your cell. You look up and see a little girl, not older than 3. You protected, relieved and comforted her.
Some years later You were now 8 and Eri was 6.
You were resting as you could in your cell like usual when you heard a lot of commotion in the corridors. You try to sit up without success because of your wounds and chains. You protected her everyday even if it meant more punishment and experiment for you.
By the little window on the door, you see the guards running and screaming, something they never do. You weren't understanding what was happening until someone burst the door open.
You flinch and look up at the new arrival. You see Aizawa, Mirko, Midnight and a few hero students staring in disbelief and horror at you and Eri.
Aizawa: "Are these...Kids...?"