Deep in the mountains of Norway, very far from civilization, sat a tiny village. Very little outsiders managed to venture into the forested area for its remoteness and difficulty on traversing. The people of the village were kind of sticky to their ancient beliefs, deities, pagan things and all that. One of those people was Agatha Levine, the daughter of a so-called pagan priest in the village. Following the ancient rules of the pagans were strict, and if you were caught doing a violation, death was imminent.
While Agatha was in the higher parts of the mountains to get water in a small stream, she saw a ball of fire floating near the stream. She was immediately scared. In their village's tradition, fire used / created magically was the sign of the devil and those who were proved of this act must be killed. She quickly ran downhill, away from the ball of fire. However, it chased after her. As she stepped on a rock, she slipped, fell down the slope and was knocked out unconscious. The ball of fire continued to go after her, and she couldn't do a thing to save herself.
When she woke up, the face of a man she described as "bright and pale" greeted her. A piece of cloth was wrapped around her with dark blood congealed on it. She must have injured herself when she fell. The man introduced himself as Brann, an archaeologist from Norway's capital, Oslo. He explained that he was going to examine some ancient ruins near the village. And to Agatha's knowledge, outsiders peering into their ruins was violation of their village's rules. She quickly held him off, but for some reason, she was quickly swayed by Brann, as if a powerful force made by deep feelings pushed her off her sense of tradition. Brann asked her to help her find the ruins, and she agreed.
They walked a rather long and dangerous path to reach the ruins, and during those times they did small talk. The sun has set long ago, enveloping the mountains in darkness. The flashlight that Brann brought was the only light that guided them along the path. And finally, they reached the said ruins, and there they agreed to sleep for the night. Unbeknownst to Agatha, she was raped by Brann. In Norwegian language, Brann means 'fire'. Yes, Brann was the ball of fire from before. And yes, Brann's true identity was Phlegethon, the river of fire. While Agatha slept, she just felt a warm sensation in her dreams, but never knew what Brann did to her.
When she woke up, she found herself alone at the base of a crumbled altar in the ruins. She didn't find Brann, and thought that he left without telling her. Seeing she can't do anything in a ruin, she left it and went back to the village. After being scolded for wandering too far, she was discovered to be pregnant. As Brann/Phlegethon's true identity was hidden during the act, the power of fire within the fetus was also hidden. No one knew that Agatha's soon-to-be born child was the "sign of the so-called devil" of their pagan tradition. Eventually, she gave birth to Cecilia, and she was the most beautiful child the village's had seen for ages. She had blazing orange hair like her mother. They didn't care who was the father, but instead they cared more about the future of their village. The position of priest / priestess would be passed onto her someday and according to one of the pagan fortunetellers, she would become a powerful leader.
However, as she started to grow up, the power of fire within her began to immerse. She came in contact with fire many times, but never got burned. The villagers began to become suspicious of her, and kept close watch. She, unlike the others, didn't like the village's strict tradition and violated it. But since she would be the future priestess of the village, she was spoiled. She always rebelled.
When she hit thirteen, while on the mountains outside the village, she was attacked by several hellhounds and harpies. Out of fear, she threw fire at them, turning them into dust. Scared of what will happen if the others knew it, she kept it to herself. This happened once every year, and luckily no one knew.
The suspicion reached its peak when she was seventeen. Out of shock, she accidentally set fire to their village's temple, burning it to the ground. Agatha went to rescue her child, she witnessed Cecilia coming out of the temple, unscathed. Fire blazed from her arms as she exclaimed, "Look at me! I'm burning!" The priest and the villagers also saw this, and quickly screamed, "Look at her! She wasn't burned! The devil! She's the daughter of a demon! Demon! Demon! Demon!"
The very next day, she was put into trial for what happened. She was threatened with instruments of torture, but she tried proving her innocence, and that the fire was accidental. The priest didn't have any choice. They have to execute Cecilia for the "magical" act. As the instruments approached her, a certain spark ignited within her. Around a few seconds, her chain was burned into a smoldering crisp by a sudden blaze of fire. From there, she ran away from the village, with her mother in the tow; but, Agatha refused to come with her for she was the 'devil's daughter'. From then on, her mother abandoned her, leaving her alone. As much as she wanted her mother back, she couldn't do anything now. She had to escape death, and she blamed her powers for it, even though at the same time she kinda liked having it. And for some reason, she blamed her unknown father for not staying by their side when things got tough. But since she rebelled many times, she knew she can survive alone. She went down the mountain as careful as she can, and managed to reach the base in a few hours.
Midnight descended on the mountains, and that day was Cecilia's eighteenth birthday. She stood alone in a quiet and bumpy road, hoping that someone would pick her up and go somewhere. As much as she knew that she didn't reached the outside world, she knew that she had to escape. Luckily, a small truck happened to pass by, and the driver 'warmly' invited her to join the ride. Actually, the driver was Phlegethon, who asked permission from Zeus to talk to his daughter for a little time. There he revealed the truth about everything, which left Cecilia even more enraged. She said, "How selfish of you!" and without hesitation, she slapped him. Phlegethon welcomed the slap freely as a sign of humility, but Cecilia wasn't moved. She refused to go with him anymore and tried going down the truck, but he knocked her out unconscious.
When Cecilia woke up, she found herself lying on beside a tree in Slottet in Oslo. A boy by the name of Nixon Thorsen (a child of Mnemosyne) noticed her. Nixon at the time was visiting Norway, his hometown. He asked if she was okay, and treated her to some bread and coffee downtown. Cecilia had to take advantage of Nixon's kindness, as she didn't have anything with her. After they had their fill, they were suddenly attacked by harpies. That's when Nixon discovered that Cecilia was a demigod. He then invited her to come with him to Camp Half-Blood, in which Cecilia agreed. After all, she had to take advantage of his kindness, despite thinking of the risks given.
They arrived at Camp a day after their meeting. Nixon, seeing that she can control fire, he thought she was Hephaestus' daughter, but days passed, and Cecilia wasn't claimed. She grew very impatient and left without the Nixon and the other campers' knowledge. Now alone again in a place she didn't know, she wandered off in New York City. A while later, Phlegethon showed up again, still with Zeus' permission; however, this was the last time. He greeted her a belated happy birthday, much to her annoyance. She quickly turned around and left him standing there, but as she turned to a corner, a hellhound jumped right in front of her, knocking her out again. Luckily, Catherine Grant and George Ahmad, members of the BC passed by and killed the hellhound. Phlegethon talked to them, and asked her to take her with them, for The Sanctuary was the only place left for her. Despite having anger on the gods, they complied to his request, and brought Cecilia to the place. There they asked Heinrich Alten, the leader of the BC, to let Cecilia join. Happy to get a new recruit, Heinrich took her in and from then on, she served under the Broken Covenant, in hopes of that one day where she'll have the power to return the favor her father gave to her.