Eri/Relationships

Family
Not much is known about Eri's relationship with her parents but it seems as though they loved her. Her early childhood was marred by tragedy, beginning with Eri accidentally erasing her father with her Quirk. Eri's mother disowned her and left her in the care of her grandfather, the boss of the Shie Hassaikai, wanting nothing to do with a daughter she saw as "cursed". Her grandfather took care of her and asked his subordinate Kai Chisaki to find out what her Quirk was. Kai discovered that Eri's power was the frightening ability Rewind, and developed a plan to use her Quirk to develop a Quirk-Destroying Drug that would restore the Yakuza to power. When the Boss refused to consent to Kai's inhuman plan, Kai induced him to a comatose state.

Izuku Midoriya
Izuku is the first person to ever touch Eri with kindness. When she tries to escape from the Shie Hassaikai, he refuses to turn her over to Kai, forcing her to run back to him when she thinks Kai would kill Izuku and Mirio Togata. Afterwards, Eri recalls Izuku reaching out to her as "different" and "kind".

During her rescue, Izuku is the first person not to call her Quirk a curse but rather kind and gentle, driving Eri to tears of joy. Since the rescue, Izuku's earnest and genuine desire to see her happy again made her grow fond of Izuku, seeing him as an older-brother figure.

Mirio Togata
She first meets Mirio at the same time she meets Izuku, although they do not react well. When Mirio finds out about what has been happening to Eri, he is riddled with guilt at his inaction and becomes determined to save her. He is the first person to give her hope that she could be free of Kai and the Shie Hassaikai.

He later invites her to the school festival and holds her in the air for her to see Izuku perform. Since then, the two have become closer, with Mirio becoming an older brother figure for Eri.

She would later successfully use her Quirk to restore Mirio's during the war with the Paranormal Liberation Front. When Mirio voiced his belief that he was using her and apologized for it, Eri instead tells him not to, because this is what she has been training for.

Shota Aizawa
Eri was unable to control her Quirk after Izuku defeated Overhaul, causing Izuku visible pain. Shota, albeit injured, was brought to the scene so he could erase Eri's out-of-control Quirk. Since then, Shota has been somewhat of a guardian for Eri, sometimes taking charge of her care as she lives with the U.A. faculty in the dorms. Eri is comfortable with Shota's presence and listens to him well.

Shota appears to have a soft spot for Eri, having bought her a matching set of cat-themed clothes while she was in the hospital for her to wear when she was discharged. He also seems to be teaching Eri about various holidays and customs. Due to Eri's severe psychological trauma and physical torture at the hands of Overhaul, Shota has been working to rehabilitate Eri while she remains under his guardianship. To this end, he utilizes the extremely positive social influences of Izuku and Mirio to help her gain better control of her emotions.

In time, he aims to teach her how to control her Quirk so that she may be able to restore Mirio's Permeation. He is very protective of her, not only out of concern for her well-being but for the safety of those around her.

Overall, Shota is very competent in his role as Eri's foster parent and guardian, doing his best to ensure that her physical, psychological, and developmental needs are met.

Ochaco Uraraka and Tsuyu Asui
Eri takes a liking to Ochaco and Tsuyu due to their kind behavior toward her. Tsu (already being an older sister to her siblings) affectionately remarks that Eri is like a younger sister to her, while Ochaco overall enjoys her company.

Nejire Hado
Nejire and Eri are shown to have a sisterly relationship. Nejire was excited to see her during the festival and Eri was shocked by her beauty. Nejire does Eri's hair, plays with her and comforts her when her horn begins to cause her pain by hugging her tightly.

Neito Monoma
After being taught by Mirio that Neito is U.A.'s "dark side", Eri becomes frightful of him, and she cowers at the sight of him when he arrives to copy her quirk.

Kai Chisaki
Eri is deeply terrified of Kai. Similar to how he treats his members, Kai only values Eri because of her use, this being her Quirk that aids Kai in creating a world with no Quirks. Due to his own Quirk, Overhaul, Kai did not hesitate to endanger Eri's life, as he could simply fix her if he acts soon enough. In addition to using Eri as a lab rat, Kai mentally abused her by telling her that her existence only causes problems for everyone around her. As a result of this, Eri developed a habit of bearing the abuse from Kai's research efforts, believing there was nothing else for her. She consequently lost her ability to smile.

After her rescue from Shie Hassaikai, Eri still wasn't able to smile. The memories of Kai's torture leave her doubtful and afraid in her new life. However, with the care of the U.A. staff and students, she is able to smile and become happy at the U.A. School Festival Arc showing she is recovering from Kai's past influences.