Opal was far more entertaining then Onyx.
I really love how Katy has matured throughout the series but it manifested a lot in Opal. Instead of trying to solve everything herself Katy is not going to Daemon and they are learning to solve problems together. A united team that is much stronger together then apart and both of them have seemed to learn that lesson well.
Daemon still has some growing to do but I see why he is so overprotective. Being tasked with keeping his sister and other Lux safe since he is so strong it is all he knows so it has to be hard to overcome that. I do hope he does learn to let people help him and not take it as a showing a sign of weakness.
Once again I noticed some typos, I did a couple double takes on some but not enough I did not enjoy the story. The writing is elegant and fast paced. Origin is already checked out from the library and I cannot wait to start it.