Rarely Pure and Never Simple by Angel Martinez

Variant children are vanishing at an alarming rate. It will take a uniquely mismatched pair of trackers to untangle a web of conspiracy and misdirection to find them.

In his isolated cabin, variant Damien Hazelwood avoids human contact as much as possible to prevent attacks of blind berserker panic. But his rare talent as a locator makes him the go-to contractor for tricky missing person’s cases and when agents bring him a troubling contract involving missing variant children, he finds it impossible to refuse.
Licensed tracker Blaze Emerson can’t help being irritated when he’s expected to follow the strange, twitchy locator’s lead on his latest case. He works alone, he’s damn good, and as a variant sparker, he has both the fire and the firepower to take on anything out there. Though he has to admit there’s something intriguing about a man who can find people with his brain.
With vastly different temperaments and backgrounds, Damien and Blaze need to negotiate quickly how to work together if they’re going to crack this case. Add in the sudden appearance of Blaze’s outlaw ex, the perils of tracking in the wilds, and a maddening lack of discernible motive or method, and they soon find themselves in as much danger as the kids they’re trying to rescue.