Daemon- Luxen, love interest
Dawson- Daemon's brother
Katy- main character
Dee- Daemon's sister
Matthew- Daemon's father figure
Ash, Andrew, and Adam- Luxen siblings
Ok, so I know there's a lot more characters that come into play than this, but these are the important main characters.
This summary won't be as detailed as some of my others, as it's been quite a while since I read the first book and I don't want to mislead anyone with wrong information, so this is just a short short review.
Katy and her mom move to a small town in West Virginia and Katy makes friends with her neighbor Dee, although Dee's brother Daemon is a complete jerk to Katy.
While Katy tries to adjust to living in the small town, she grows closer to Dee and more curious about Daemon.
When Katy and Daemon get in an argument, she walks in front of a truck since she's so angry she's not paying attention. Daemon turns into a beam of light and rescues her from in front of the truck. Katy finds out Daemon and Dee are aliens called Luxen, and there is another alien race called Arum which are the Luxen's enemies.
The government know about the Luxen being on Earth, but allow them to stay as long as national security isn't breached. Daemon tells Katy the reason he has been mean to her even though he's attracted to her is that his brother Dawson became involved with a human girl called Bethany and they were both killed.
Three Arum attack Dee, Daemon, and Katy later on in the book. Two are defeated but the 3rd comes back after them and Katy kills him with obsidian (hence the title).