Grayson Miller was born without understanding emotions he can only imitate them. Because of this when ever he tries to help someone it ends badly which has caused his family and the people around him alot of grief and problems to the point where they don't like him.
he is mostly misunderstood by the characters and by the readers. he has good intentions at helping the people but since his brain was already damage from his own pheromones since he was a child, that's why his method of helping was not always good.
He constantly tells people they're going to be his one true love then ghosts them days later, as shown in the beginning. Also he in another series pushed his brother in front of a bus and later convinced same brother he'd raped a dog while in rut. In his own twisted mind he considers those good actions because it got his brother out of school, and got him to let out his pheromones, and did not consider the physical and mental toll they took on his brother as important.
I don't understand the story exactly like is Miler a bad person or not why do they hate him?