You're dead wrong when it comes to Grayson.
Grayson is far more dangerous than you think.
Grayson vs Josh and Grayson vs Dane, if none of them use pheromones, Grayson would win if he fights seriously. Because it's not only about releasing pheromones, dominant alphas have other advantages, and Grayson is the extremest form + he doesn't have bodyguards.
Josh already got an idea in a KMIYC side story, but not to the full extent on how dangerous he really is.
Actually this manhwa adaption just skipped a phone call between Josh and Chase, about kidnapping Grayson, but they are not interested in killing him.

You know I have this kind of mixed feeling about grayson..I love him in this manhwa but then I keep remembering how he treat chase that make him traumatized..it's make me love but hate him in the same time..but yeah I think I hate him more and have tendency to let josh kill him(even though I know it's not going happened because Dane and Josh are friends and of course because creator of this manhwa..pftt)..gosh I hate this kind of chain manhwa