While I still think Cassie is the main character she sort of steps back in The Infinite Sea and several other characters take the leading role. That disappointed me since I enjoy Cassie and seeing her struggles. Having been reunited with her little bother Cassie just wants to keep him safe but that is easier said then done in a world full of lies and deceit. Not to mention a little brother who has changed a lot after being in a boot camp training to kill.
I did not overly care for Ringer in The Fifth Wave but she sort of grew on my in The Infinite Sea. The last forty percent or so of the story focused on Ringer and while it was nice learning her back story it was a bit long winded.
Despite not having Cassie as the character with the most book time I enjoyed The Infinite Sea and eagerly look forward to the release of The Last Star later this month.