I love this trilogy! When I finished this book, I thought, "Now, this is what I call a good YA Fantasy novel!"
My favorite thing about The Immortal Game trilogy is that Edie does not have informed attributes--traits a character is said to possess, but is not shown to posses. I can actually see that Edie is smart, resourceful, mature, and most importantly, learning. Some of the YA novels I've read have someone (character or narrator) telling me that a character is one way, but Ann Aguirre continuously shows who her characters are.
In Infinite Risk, Edie goes back in time to try to save Kian from going into extremis (I.e. complete mental collapse) and getting involved in the immortal game. There is a chance she will change nothing, there is a chance she might change everything, and there is also the possibility that she is only creating a divergent timeline from her own timeline. But no worries, like any good Whovian or Winchester, Edie has searched the possibilities and come prepared with Aegis in one hand and money in the other.
Throughout this novel Edie is dealing the loss of her mother, the loss of Kian, and the loss of the potential life she could've had outside of the immortals' game. She is constantly having to adult while also protecting her boyfriend who doesn't know her, doing high school homework that she could do in her sleep, and while waiting for the immortals to find her--no biggie.