France. Eleanor grew up in Suburb 93, one of the worst slums in France. She was surrounded by incredible violence and corruption.
Church. To get away from it all she ended up attending church daily at the tiny, underfunded Catholic Church in her neighborhood. She found a calling in the church, and ended up becoming a nun at the age of 18.
Science. Unlike what many thing, the Church does NOT dispute science. They merge science and religion, as does Elle. She turned out to be a scientific prodigy, and got a degree in Astrophysics while working as a Nun.
Leopold. She eventually drew the attention of the Society of Leopold. She was drafted into their Holy War, and spent several years aiding in study needed to hunt vampires. She went on more then a few Hunts herself...and the memories haunt her.
Awakening. Her crisis of faith caused by the atrocities she committed shook her...and ended up opening her up to the Song. She fled the Society, and they haven't forgiven her.