I think every miller is a dominant so no thats not it.
Quite a spoiler......
grayson has a condition from birth which makes him unable to read, show, and understand emotions. It's a word I am unfamiliar with so I don't remember the term sorry. some call him neurodivergent but theres a specific scientific one. He underwent therapies since hes young bc he is harming his family unintentionally. He was also constantly being monitored then. (thats why he appears to be spoiled from other readers pov) He grew up just mimicking emotions, learned when to smile, what actions to take at which situations by watching others, like that. He also always has good intentions but with the wrong solutions. But he is constantly confused if he was told that it was wrong bc he focuses on the good outcome. He explains his reasoning too and he listens when reprimanded but still doesn't get it.
So I wouldn't call it a simple character development when he became a better person through Dane's presence, no. It somehow downgrades him into those other toxic mls who felt guilt and regret in the end but still did horrors while "sane".
I was like that at first until I learned that Grayson seriously has some mental issues. Like fr, he's not doing these things out malice or anger, he genuinely thinks he's doing the right thing, due to his mental issues and also due to how he was improperly taught. Grayson is shockingly a romantic because he's been obsessed of finding his one true fated mate for a very long time.

Ykw, no amount of character development could make me like Grayson. To fvck with "He just don't know about the concept of emotion because he is a Dominant Alpha" I DONT FVCKING CARE! HE SHOULD JUST DIE! HE IS WORST THAN A FVCKING SCUMBAG! EVERY MALE LEADS IN THIS UNIVERSE SHOULD JUST DIE except Chase