Um

OK

You make a mistake if you think that Grayson is solely reponsible for how Chase became. Grayson certainly gave Chase trauma because of his misguided help, that is a fact, I'm not whitewashing what Grayson did. But they have parents, other siblings and the author made Chase an idiot.
And what you're completely missing is that Chase is a dominant alpha. Being violent has to do with him manifesting, not with Grayson. He might have manifested late and the impact was was much weaker than for his siblings, since he understands emotions etc, but it still had an impact.
Him deciding not to release pheromones initially had nothing to do with Grayson. It was him not wanting to sleep with others without love etc. driven by instinct. But being a dominant alpha forces him to release pheromones, because the consequences not doing that are severe. His father became emotionless, because of that and his father was initially more normal than Chase and had trauma from his parents. Chase could have completly avoided dealing with Grayson, if he went to the hospital on his own.
Chase even prefered Grayson over dealing with their dad, and make no mistake his dad would have made sure that Chase releases pheromones one way or another, he monitors his children.
I'm not denying that Grayson gave Chase trauma and Chase suffered because of that, but you can't make Grayson responsible for Chase's violent behaviour.

And Grayson suffered in his story, in a different way, but he did suffered.
He actually earned his happy end with Dane, and he let Dane be the one to decide. That's something I can't say of most alphas.

1, not reading all that, 2 he is the main reason why he turned out that way and you cannot deny that in any way shape or form because even the author herself has said that he is the biggest reason why he ended up the way he is he even has extreme trauma when it comes to intimacy he literally was made to believe his first time was with a fucking dog because his brother just wanted to make him think that