Kindred Spirit by Noah Harris

Jacob:

Sometimes, the world isn’t what you think. There are more horrors and wonders than you ever thought possible. That’s the kind of life I’ve lived, changed forever by the world and its secrets. Former soldier and now federal agent, I’m sent to help and hide those secrets. It should have been simple. Find the target, find out if he’s more than he appears, and report back. And if it comes to it, protect him from danger. Protect Levi.
But it’s never that simple, is it? And Levi didn’t turn out to be that simple either.

Levi:

Having your own spirit companion might sound fun in theory, but in practice, it sucks. Don’t get me wrong, I love Louis, or Lou for short, he’s my best friend, like a brother really. But that doesn’t mean his existence hasn’t been a pain. We’re always on the move, never staying in one place too long. After a year in Gilcreek, Montana, the idea of moving on sounded good. Then this new guy checked into the motel. Jacob claims he’s an artist, but he looks like he just walked out of a fitness magazine. Turns out there’s more to him than meets the eye. Now everything has blown up in my face, and we’re running for our lives.
My life was never easy, but things just got a whole lot more complicated.