There are two kinds of vampires in the world: those who hate being one and those who thrive on the blood. Those who are humans turned into monsters, and those who are monsters wearing human skin.
Therisa was born a vampire, unlike her parents, who were humans and got turned into vampires later in life. Naturally born vampires like Therisa and Eris are rare, but they all shared one common trait. They all lacked humanity.
To be born a human, and live as one, to be fragile, weak, and hopeless in the face of danger, then get turned into an all-powerful and immortal vampire, that puts many people in an unstable state of mind where they can't be at peace with their power and deeds. Many of them, and even after they get used to their power and the bloodshed, still hold themselves back and try to maintain a resemblance to who they were before.
