I wasn't expecting that.
Thalia, or Storm, the FMC, is a troubled woman with a lot of trauma. I really related to her; her overwhelming loneliness, and depression, not to mention the trauma, it made me think about myself a lot while reading. I had to stop a few times to remind myself that I am not Thalia, and this is a story.
Tristan, or Shadow, the MMC, is an obsessive stalker that terrifies, yet gives comfort, to Thalia. He has a lot of trauma, as well, and that shows in a lot of the decisions he makes.
Tristan is always there to save Thalia, even if he does it as Shadow. I loved watching their dynamic morph, and finally admit the truth. They make each other feel. The psychological aspect of the story was good, too. There was so much tension, you were questioning what you thought you knew, you were happy one minute and pissed the next.
That plot twist was unexpected, and the cliffhanger broke my heart.