Eri

Eri is a timid and innocent little girl and as such, she wants no part in Overhaul's horrid plans. During her childhood with the Shie Hassaikai, she repeatedly tried to resist and escape her captivity only to be stopped and recaptured every time, leading her to accept her fate as a prisoner. Having mentally accustomed to this treatment, Eri does not cry or scream when somebody intends to harm her. Instead she remains silent while trembling in fear, knowing that she doesn't have a choice but to accept whatever will happen to her. After remembering Izuku Midoriya helping her up and holding onto her, she cried upon realizing that his act was out of genuine kindness.

Eri was lead to believe by Overhaul that her existence only served to bring pain and suffering onto others, which lead to the villain exploiting her desire not to harm others and nearly return to his clutches. Despite being in a state of fear and cruelty, she would rather give herself in rather than believe that others are being harmed because of her.

After her rescue, Eri still remained timid and was still psychologically affected by her past treatment, with her being unable to smile due to not knowing how to and not having any experience of happiness. During the School Festival, however, Eri overcomes this and feels an overwhelming burst of joy while witnessing the performance, leading her to smile and be freed from her past.

Thanks to being nurtured by U.A. and the encouragement from Izuku and Mirio, Eri is now more optimistic and determined, no longer seeing her Quirk as a curse and starting to control it. When Mirio expresses reluctance towards the idea of her giving him his Permation Quirk back, Eri tells him not to be guilty as she has been training for his sake, and successfully restores Permeation.