He was lying when he said that to chase about doing it with bliss. If you only read the novel you will understand his character very well, sadly this manhwa adaption doesn't show that much. Grayson has no intention of Doing that to Bliss his omega brother. He was even much closer to Bliss than his other siblings, it was shown on Bliss novel. Grayson was the one who been taking care of Both Bliss and Chase. And regarding the "Dog part" He did that to chase in order to have him release his pheromones, As we all know chase doesn't want to release his pheromones and Grayson know that to much build up pheromones will kill a dominant alpha in order for that not to happen he lied to chase, to force him into releasing his pheromones. Although that's kind of crap or trash move he did that with an intention of helping chase but here's the thing Grayson cant feel emotion, he copy or mimic emotions, so of course he believes that what he's doing is helping chase but instead of helping him he give him trauma.

Oh, yeah, because the guy who threw his little brother down the chimney for giggles when he was little, psychologically tormented him for over a decade, and was open and fine with raping his other younger brother if the opportunity ever presented itself, is exactly the kind of person that should want to take care of a baby. Honestly, I like this author but would also like to know what they were smoking when they made Grayson, because his character consistency is a pile of crap.