Wild Reckoning by Lynn Hagen

Stewart’s life has been turned upside down—learning about a world of shifters, discovering his connection to Killian, and facing a dangerous threat all at once. Yet, it’s Killian’s fierce protectiveness and his warmth and kindness that gives Stewart hope for a future he never dreamed he could have.
Killian Everhart is a bear shifter who never expected to find his mate stranded on the side of the road, a human with a painful past. As their bond deepens, so does the danger surrounding them. A ruthless criminal group is after something hidden in Stewart’s house, and they will stop at nothing to get it, including threatening Stewart’s young nephew, Ethan.
But when the enemy strikes, Killian must unleash the full power of his bear to keep Stewart and Ethan safe. With danger lurking, he will do whatever it takes to protect the family he’s only just begun to build.