can someone explain exactly what grayson went through for so many of ya'll to think that h...

Grayson is Apathetic meaning he has no emotions or can't feel them from when he was born he has been like that no emotions. He is literally following what his father (Ashley) tells him to do. Grayson has no Personality currently cause whatever he does he just mimics or copies other people, he doesn't know how to help people or what other people are feeling it's just sad. He has went through shit like his father(ashley) almost strangling him to death when he was like 8 or 9 years old, but Grayson doesn't realise it was bad for him that was so sad honestly he didn't know that it was abuse also.
If you read his story you might be able to understand him.
And Grayson plays pranks but doesn't realise to which extent he can go with the prank so he overdoes it which leads to harm like in Chase case, Grayson just trying to fit in and be close with his family but yeah nonetheless he hurts them. He actually cares for Chase he wants to protect him but doesn't know how basically so he does that twisted stuff.
Read his Novel
Lol Dane describes him well - "When she's happy, she moves her ears. It's incredibly cute. Sometimes, when she gets lonely because of me, she cries, and while I feel sorry, I find it so lovely that I just want to shower her with kisses. Plus, she gets sulky often, and every time that happens, she looks like a puppy to me, and I go crazy. Sometimes I even want to check if she really doesn't have a tail.
And that girl, she knows she's pretty. Sometimes, when I call her pretty, she moves her ears because she likes it. Cute, right? Don't you think?"
Well u can understand from Dane why people love Grayson ig, Dane actually helped Grayson to feel emotions in his life

I read the novel, and no I can’t defend him . He’s really born crazy and does crazy going as far as to attempt killing his dad, attempt grape his brother, and letting others hurt themselves as he hurts them (su1cide). He messes around and fakes his emotions, at least until he met Dane. Atp, I just accept that he’s irredeemable but only grew attached because of the novel. Other than that, he’s objectively detestable, especially when he doesn’t have a sad backstory unlike Chase.