Bo is a Succubus who grew up in an adopted human family, unaware of her non-human nature and of the Fae world she descended from. She began to feel "different" when she entered puberty and didn't know she was not normal until she accidentally killed her high school boyfriend by draining his life energy during her first sexual encounter. When she told her parents what had happened, they broke the news to Bo that she had been adopted (see "Raging Fae"). Not knowing what she was and what she had done, Bo hated herself and ran away from home, exchanging her previous life for one without family or friends, moving from place to place and assuming a false identity whenever she killed again.
In the first episode, Bo saves a young human woman, Kenzi, from a rapist who had surreptitiously drugged her with a "roofie" in her drink. The two quickly become friends and Kenzi decides they should team up to create a Fae/Human detective agency. Confronted by the Fae leaders of the local territory with a demand for her to choose a side – either "Light" or "Dark" – Bo declares herself neutral, deciding instead to side with humans after Kenzi risks her life to find out where Bo had been taken by force and what they were doing to her. Most of the Fae considered Bo an unknown entity that should either be eliminated as a risk to their secret existence or exploited for their benefit. Throughout the season, Bo learns more about the Fae world and herself while she searches for information about her origins. Along the way, Bo also develops romantic relationships with both Dyson, a Light Fae wolf shapeshifter and police detective; and Lauren, a human doctor and scientist in servitude to the Light Fae.