This is a DNF review. Only 60% was read, the rest was skimmed. 
 I'm a fan of Kelley Armstrong's books so I was ecstatic for this one, especially after reading that synopsis. We need more sibling centered/family books in YA. 
 I actually really liked SEA OF SHADOWS when I first started reading it. The book had pretty good pacing, interesting characters, and more than a few secrets I was anxious to figure out. But after two hundred pages of all that with no rise in the plot, trying to finish this one became tedious. 
 Character development is pretty much always necessary in a book, but the development in these characters didn't always lean toward growth. After awhile, it seemed like I was reading about an entirely new set of characters, almost all of them had changed and read differently than they had in the beginning. The love interests I had liked in the beginning became soft and sappy while one of the main characters turned into more of a damsel in distress. 
 SEA OF SHADOWS was too much of the same thing for too long. After the initial bout of action and fast pacing in the beginning, it leveled out and it seemed like nothing was happening for awhile. And there is a point where you just have to say 
 This book hooks you in at the start, which was great for me. However, if you are the type that tends to lose interest or patience with a book towards the middle because things are dragging out, SEA OF SHADOWS may weigh you down. Otherwise, it's not too bad of a book.