Idk I could be wrong but, Grayson traumatized his brother Chase (from the story kiss me if you can) Josh hates Grayson because he made Chase believe that he had his rut with a dog. (He didn’t, he was just made to believe he did) it traumatized him so much he even developed a fear of dogs. So I’m assuming it’s like a form of revenge??? I could be wrong though.
Chase avoids omega and go through so many pills because he hates sleeping around like what other dominant alpha do, this was even before the Grayson incidence which made Grayson pushed him to release his pheromone in some way. If you read the manhwa carefully you should see Chase repeatedly says he is disgusted that alpha sees sleeping around as normal and continously overdose his pill whenever his pheromone builds up.

omg what did he do in this time line to deserve this poor man just wanted to see his first birthday partie