Eilerias was born with the name Sylvanna Fir'ryn in Falwood to a high elf father and a human mother. To her knowledge, she was abandoned shortly after her birth and spent her youth in orphanages in Vel Anir. Due to the nature of Vel Anir's inhabitants, she was shunned and only found comfort in the shadows as a child.
She discovered the way of the light at 14 years old and decided to devote her life to the holy Lord of Light. After she came of age, she was able to find work in the church as a healer in exchange for a place to live and worship.

While working in her church, she met a woman, Gwendolyn Vollmund, who had began to send shady people to visit Sylvanna in need of healing. Sylvanna jumped at the opportunity, eager to help anyone in need. It seems like she was always kept in the dark on those she's healing, but she rarely asked questions. Maybe its because they came to her at all hours of the night and she's too tired to converse. It turns out that she had been healing criminals and breaking rules within the church that would have resulted in her being imprisoned. As if being elven in Vel'Anir wasn't enough.

That night, Sylvanna lured a poor young girl who looked like her out into the Falwood and murdered her, leaving a burning body with some of her own belongings scattered nearby while she fled to Alliria with Gwendolyn. In the cart ride, she was given a new name. Eilerias. It seemed like a joke, calling the frail young girl a name which meant brave and strong, but the name stuck and the girl would continue her life in Alliria on her own.

Little is known about what she did during the next few months, but one day she arrived at the door of the archives, soaking wet from the pouring rain, where she reunited with Gwendolyn and was given a place to stay in exchange for work. Eventually, she joined The Cherry Rose because of her healing abilities and helped them in a heist, as well as other petty jobs.

Unfortunately she had forsaken her vows she made to her god and fell in love with another member of The Cherry Rose, soon finding herself pregnant with her daughter Lucinda. In an attempt to mitigate the damage within the church, she was adopted into the Briarthorne family.

Since breaking her vows, her shadows have grown strong, completely taking over her body at some points, using her to gain power for their own. The shadows like power, they crave it. They use her cute and innocent appearance to lure in unsuspecting people who have power and siphon it off as they lie together.