They're not abusive. It was grayson's lack of empathy and understanding of human emotions that made him like that and his papa (ashley) just punished him for almost killing their mom (koi is ashley's partner) and locked him in a room. Ashley taught him about what he needs to know about emotions to guide him and but was kinda strict.
They are all required to release their pheromones especially the extreme alphas so they won't be like Ashley who lost his mind and affected his brain (i think grayson called it disability in his story). Grayson's thinking was abnormal and tried to help chase in a way that he thinks is good but so traumatizing to chase. I dont wanna spoil everything to you but it'll be resolve in a way but chase wont forgive him easily.

Can someone spoil me miller’s past? Cuz i cant imagine miller’s parents being abusive cuz from the panels theyre shown they look chill