His Secret Alpha by Chani Lynn Feener

Sky Tancredi has had a secret crush on his best friend’s older brother for as long as he can remember.

Too bad Kian has never seen him as anything other than a kid. Now that he’s graduating college and presented as an omega, Sky hopes things will be different the next time he runs into the alpha. The plan? Casually bump into him at the Christmas parade and blow Kian away with how mature—and hot—Sky now is. Too bad Sky’s body doesn’t stick to the program, and instead of coming off as a trendy, cool omega, Sky goes into heat at the first sight of the older male.
Kian Erksine is an Intergalactic Detective with the IPF.

But he pretty much hates his job. He’d thought it’d be all excitement all the time, but instead he mostly finds himself handling petty crimes. Now that he’s back on his home planet, he needs to think up a way to explain to his family that he’s not just there for the season, but to stay for good. As if that isn’t difficult enough, an awkward encounter with his younger brother’s best friend suddenly has Kian all sorts of confused about other things as well. Like whether or not Sky has always smelled that good.

When Sky randomly goes into heat, Kian ends up giving him a hand. It was only meant to be a kind gesture, but now that he’s had a taste, Kian can’t seem to stop thinking about the creative omega.

Or how badly he wants to make him his.