Titus is lost after his parents' death. His sister has vanished, he's starting to hate school, and his house feels incredibly empty. And then a strange teenager enters Titus's house through the upstairs mirror, and drags Titus to another world. This world is like Earth but in some ways different. Everyone on Earth has a "twin soul" there; a person that looks, acts, and thinks like they do. When a person dies or is injured in one world, their counterpart suffers the same wounds.
Titus is the twin soul of a newly-orphaned prince. This prince, Atreus, is like Titus - but in some ways different. He can talk to angels, for one thing. Atreus has brought Titus to his world in order to fulfill an impossible prophecy, a prophecy nobody can truly understand...
In Titus and Atreus's defense, I read it while under the influence of a mild cold. That may have tempered my enjoyment a little. I ended up feeling fairly neutral about the book; I didn't love it, I didn't hate it.
It just felt very haphazard to me. Things happened for no apparent rhyme or reason, and were never fully explained. Some parts felt extremely implausible, so implausible I wasn't willing to suspend disbelief; some parts just felt cliche. The romance(s) were awkward and none too original. The conflict - oh no, an evil king is attacking us - didn't hold my interest.
Also, I really didn't like the ending. At all.
There were parts of the story that had a lot of potential - for example, Titus begins remembering some of Atreus's memories, memories he couldn't have had access to. I really wanted to read more about those aspects of the story, but sadly they were never really explored.
Titus started off mopey and emo, but improved quickly. By the end of the book, I though he was decent. Atreus, in contrast, I still don't understand. Most of the side characters were a little vague and predictable. As mentioned above, the characters' romances were just awkward and not particularly interesting. Plus, everybody basically paired off, romantically, so there wasn't much intercharacter tension at all.
Also, villains can be the best part of the story, but the villain in Titus and Atreus read as very lackluster to me.
Myers is a decent writer, and the writing was fine. I don't have any complaints to lodge here. However I didn't find much that stood out, either.
End Result: two stars. I was not impressed.