Alestria City was founded as a result of the coronation of Queen Kitra and her lover, Queen Celeste Angeal. To commemorate the joining of the races, Alestria City, founded on both sides of the now permanently open Gates to Heaven, was created. It was a city filled with promise and hope, and as such both demons and angels moved to live there, hoping for a future where both races could coexist. One of the migrating families was the Illuvia family, where Lucian and Senna, both soldiers who served under Gabriel Angeal as Purifiers of Darkness, they married and became joined as one family. With hopes and ambitions of being pioneers of peace, Lucian and Senna moved to Alestria City, retiring from their work as Purifiers of Darkness.

Ophelia was the first born child of the Illuvia couple. She was born with a mutation, she had two spike-tipped tails coiled together on her rear, dreadful appendages that were often looked down upon by other angels. Angels born with mutations like this were a result of their souls not being properly cleansed from their time living and dying as humans. Thus, Ophelia was no doubt still bearing the weight of the burdens she suffered as a human. Despite this, Lucian and Senna chose to hide the mutation, keeping it secret. As former Purifiers, they were obligated to report mutations, since it was part of a Purifier's job to help cleanse young angels by sending them to the purification center. Knowing it could take years to fix their daughter, the couple opted to cure her themselves, not wanting to be separated from their child.

Apricot Academy was a school made for angel and demon children to mingle and learn together. It was run by a mixture of angel and demon staff, and it was an experiment to see if children could grow and learn alongside the other race in order to foster good relationships on both sides. One such demon, Katua, became close friends with Ophelia. She had been taught by her parents to hide her ugly tails, and, while afraid, Ophelia and Katua became friends. They were often studying together and walking around the city, exploring as their own little duo. They hardly even noticed that in their class, everyone else split off into groups of demons and angels, with no intermingling between them. This isolated both Katua and Ophelia, and both girls became targets for bullying as a result. The demons would throw sticks at them, the angels would pretend as if they didn't exist. While it hurt and was scary, as long as they had each other they would be okay.

A boy was next born in the Illuvia family then. He would be named Laertes, and just like Ophelia, he too was born with a mutation, though unlike Ophelia his was much less visible, merely a white scar on his face. The purifier couple chose to allow him to remain with them as well, not wanting either of their children to go through the purification facility's practices. Ophelia and Laertes had a complicated relationship. They were siblings and sometimes they got along, but they had a lot of resentment for each other as well. Ophelia was used to being the only special one in her family, but as her parents divided their attention trying to cure the mutations for both of their children, Ophelia and Laertes would go into competitions to vie for attention. While there was love, there was also hatred as well.

As they grew older, Ophelia and Katua had a terrible incident. Inspired by the increasingly radical speeches by Baron Messiah, the young demons abducted Ophelia and Katua. They beat them up, telling Katua that demons could never be friends with angels, that demons could never live in peace. They broke Katua's arms, ripped off her tail, and told them they would sell them both to Messiah if she didn't start beating up Ophelia. Katua chose to fight back, and all that was left of her by the end was a broken soul piece that Ophelia cradled in her pocket arms as she was mercilessly abused for days until her brother, Laertes, found her and called for help. Ophie isolated herself after that, refusing to talk to any demons, viewing them as evil, as violent. At her first chance she signed up to join the Angel Knight program to train and serve directly under Queen Celeste in the Heavenly Palace. She made sure to hide her disgusting mutations and trained hard with a single goal in mind - to fight and kill demons for the sake of angel kind. A few years later, her brother would join the training, and the Illuvia Siblings both became Angel Knights working under Queen Celeste.

For many years the brother sister duo worked together to serve Queen Celeste. They were at her side, comforting her when Queen Kitra's head was delivered to them on a spike at Baron Messiah's hands. They were the only ones Queen Celeste trusted with the mission. Go undercover to demon-infested Earth as demons, and find a way to assassinate Baron Messiah, bringing an end to his evil. Ophelia and Laertes made a decision to compete against each other to see who would be first in completing the mission, parting ways as they reached Paris's ruined gates.