Color of Blood by April Kelley

For fated mates, going from friends to lovers should be a smooth transition, but Ladon and Magnus have never had things easy.
At twenty years old, Ladon knows he’s too young to be Saint Lakes’ Alpha, but no one listens. Not even his mate, Magnus, and he’s Ladon’s his best friend. Magnus is out of town on a dangerous investigative mission when Ladon shifts for the first time. Ladon and Magnus have waited years for the day because they couldn’t bond until it happened. Almost as soon as it does, Magnus goes MIA, leaving Ladon to wonder if it just isn’t in the cards for them.