Into the Split - Tris Lawrence

Watch out.
Don't fall into the Split.

Nikolai is a Dreamwalker born into a family of Weather Witches. His boyfriend, Seth, is an Empath, anchoring him so that Nikolai won't accidentally open a pathway between the physical world and the Dreamscape.

But Dreams are slippery things: they can attack, and they can trap, and Shadows live in the dark spaces between worlds. Shadows escaped the Dreamscape and came to Nikolai's world when he was a child. They fed hungrily, drawn to those of strong Talent, killing Nikolai's family and destroying his home.

Nikolai and Seth have have been on the run ever since.

When the veil between the Dreamscape and his world cracks open again, Nikolai is shocked to meet his doppelganger from another world, Nikita. Claiming that Nikolai's life has been in her nightmares for months, Nikita promises to save him, but the actions of her and her friends draw the Shadows to them wherever they go. And worse yet, they quickly realize that their worlds are linked: if Nikita cannot save Nikolai, her own world may be lost as well...