Sam (Fearless, Book 2), by Francine Pascal
As Sam begins, Marco is dead at Ella's hands, and the neo-Nazis have, for some reason, decided that Gaia did it. As a result, CJ (the guy who attacked Heather back in Fearless) has now been given the task of killing Gaia. Once she learns that CJ is determined to kill her, Gaia makes two decisions: 1. to find her father, and 2. to have sex with Sam. We don't actually see very much effort on meeting that first goal; we mostly focus on the second.
Heather feels her hold over Sam slipping due to Gaia's influence. So she has decided to have sex with Sam as well.
This volume is actually kind of thin on plot. It does, however, have character introspection. And chase scenes. It has lots of chase scenes.
We see the changes that Gaia's presence has made in the lives of Ed, Sam, and Heather. We also see a lot of Tom's thoughts about Gaia and about Gaia's mother, Katia.
We also see that Heather is tired of being the Queen Bee and that she has gotten herself into an untenable position. Her parents have fallen on hard financial times, but she cannot keep her position in the school social structure if she admits to it. So she is stuck. She is like the proverbial person riding the tiger -- she cannot get off the tiger, or the tiger will eat her. I actually felt a little sorry for Heather. Not quite sorry enough, though, since we also find out that Ed was her first love, and it all came to an end when he had his accident. Even when looking through her eyes, she seemed very shallow, breaking up with someone she claimed to have loved simply because his legs don't work. If that's love, I think I'll try something else, please.
Speaking of love, we see a lot of Sam's conflicted feelings about Heather and Gaia. He thinks that he probably loves Heather. But he is drawn to Gaia in a way that may be love, as well. I get the feeling that he doesn't love either one. Or he's poly. Him not loving either is more likely (not that he will never love either, but he doesn't yet).
Gaia decides that since she is probably going to be dead soon, she had better get on with propositioning Sam. She goes down to the park and finds Sam. There's a very detailed passage showing the way that her emotions are all over the place while they sit side by side on the bench. However, before she can proposition Sam, Heather catches up with them, and gives a note propositioning Sam to him. After Heather and Sam leave, CJ turns up and we get the first chase scene of the book, as Gaia flees.
The book ends in an extended chase, in which Gaia is chasing someone who looks like her father, and CJ, Sam, and Tom are all chasing Gaia. This chase leads pretty much directly into the plot of the third book in the series, "Run".
We find out who the "L" in all of those emails from "Fearless" is. Though I reserve the right to be skeptical about whether we know everything, based on things I have read about future books in the series. I'll have to read the next few books before I can be certain that what we've been told is actually what is going on here.