I picked this up on the strength of the positive reviews and because I enjoyed Mixed Signals, but it fell really flat for me. In this world some of the human population develop into Protectors (humans that shapeshift into dogs) and Handlers (the 'dog' handlers). If one dies, the other can't survive. They are strictly monitored and limited by their perceived roles and the Big Brother-style, Institute, that controls them.
Alex, a Protector, lost his handler 3 years earlier but didn't die so he is a conundrum that the Institute scientists monitor closely. They are constantly doing 'tests'. I think that is the extent of the author's knowledge of medical terminology... 'tests'. They are really dumb scientists.
In his human form Alex could have been any guy from suburbia. In his dog form he is just a dog. Not a wolf. Not sexy. Not dangerous. Not that smart. Not even adorable which might have worked better with this incarnation of the shifter trope. Just a dog. Like my dog. The handlers treat the protectors like domestic dogs too. "Sit'. "Stay'. 'Good dog'. etc.
There was a briefly introduced sub-plot about community bias towards the Protectors (as in treating them like dumb dogs and only speaking to them through their handlers) which I thought was interesting but it didn't go deep enough for me.
Alex is depressed and unable to move on from his previous handler's death. He goes on and on about it constantly. When he's not thinking about it, his two friends, Sam (a female Protector) and John, her handler, are inserted frequently into the story to talk even more about Alex's problems. Sam in particular is so annoying. Sam is a typical female mm character. She is bossy, interfering and crosses all boundaries of friendship. The whole thing with them and Ryan is a shock. It could have been more meaningful but it's just accepted and not explored or resolved by the end of the story.
There is a killer after Alex whose identity is very obvious. Mystery plots in romance are usually fairly slim and this is no exception.
I came to the end of the review and realised I didn't write anything about the other MC, Marcus. I guess that's telling. I didn't get to know him and I didn't feel their romance at all. The book ends with a HFN ending which is quite suitable seeing as Alex is not really over his first partners death.
I was just bored by this. I had to push myself to finish from the very beginning. Not my kind of book.