I believe Grayson is a sociopath. And Ashley, not knowing how to deal with the fact that Grayson's grandfather and Ashley's father were the same way, ended up acting this way with Grayson, teaching him certain things, such as only retaliating in self-defense. And so on. Of course, I'm not saying what he did to Chase was right, but we can understand the reasons. So much so that in Chase and Josh's book, Chase is feeling unwell because of the pheromones and Grayson calls Josh. When Josh asks what Grayson would do if Josh didn't show up, Grayson says he would kidnap Josh because of his brother. This made me think that Grayson really believes he did the right thing with his brother... Here's my research on sociopathy, and I found it quite similar to Grayson.
Spoiler!
How to identify a sociopath?
✕Lack of guilt and remorse: They feel no regret when hurting or harming others.
Impulsivity: They act without thinking about the consequences, often exploding in anger for trivial reasons.
Manipulation and superficial charm: They can be very charismatic on first contact, using this to manipulate and get what they want.
Disrespect for laws and norms: They have difficulty following rules and frequently get involved in conflicts.
Sense of superiority: They are often egocentric, vain, and believe they are right in their actions.
I don't know what to say, I don't have money for therapy so I read yaoi.