I definitely think this murder was much more personal to JY than just done to impress daddy dearest.
Just think about it.
JY had to live a lie. He had to tell CPR that he lived as one big happy family. One dad, one mom, 2 sons and a little sister. Yet the stark reality was that was just a façade and he had to fake it once a week in front of the social worker. Josh Young during the entire time JG had him he was only 'allowed' to stay over at Amanda's two times. "Allowed' to really be a part of his pretend family.
I think Josh Young hated that he was tossed aside and left out of the real family unit. The other kids had their own bedrooms while JY had to go stay at Cassie's in a spare bedroom.
I think he resented the hell out of Trey because Trey was known as the good son who had a supportive father that loved him for him and did a lot of productive things with him. I even wonder if he was told by either JG or Amanda 'why don't you act like Trey?' because Trey was known as quiet, easygoing, and very family oriented.
I just think this was very personal with a lot of rage pent up inside of JY. He had wanted to be with his dad but yet most every night he was told to go stay elsewhere and couldn't be with his 'pretend' family he was suppose to have.
IMO
Ocean...you and I are thinking so much alike on this one! I think EXACTLY the same thing....that's why I even doubt whether it was all Gouker's "agenda" to begin with. I think what probably happened was that Gouker would say things about Terry Zwicker...which he also said on the stand that he didn't like him. So he would probably say this stuff in front of Little Josh. Cassie stated that Gouker had mentioned "eye-for-eye" talking about Amanda's abortion -- I believe Gouker was saying that in the heat of the moment...like Amanda wants to take my baby...how would she feel if I took her baby from her? The way Cassie said it also implied that he was just kinda venting to her...but I'm sure he did this venting a few times in front of little Josh.
Then you have on top of that, like you said, this thing where Little Josh was kind of the "outsider" in Amanda's family...Amanda had her own family unit with Trey and Kenzie, and Gouker obviously wanted to be with Amanda and by extension he would be a part of that. If he wanted to be with Amanda, he had to be with her kids. On the stand, it was clear that Amanda didn't think much of Little Josh even before Trey's death. It didn't matter to her where he slept, or whether he had a room like Trey and Kenzie. He was Gouker's and she didn't care about him, other than she had to deal with him 'cause of her connection with Gouker.
So here you have Little Josh staying at Cassie's, with Big Josh spending most days and nights at Amanda's and with Amanda, and so by extension with Trey 'cause Trey was naturally at his mom's some of the time. Meanwhile Little Josh has to go over to Trey's house to see his own dady.
I feel like all of this built up and built up in Little Josh, and he finally took it all out on Trey. It was not that he had a specific beef with Trey, it was just that Trey was who he directed his resenment at for everything wrong with his relationship with his dad and for his living arrangements, etc.. And he was jealous of Trey, IMO.
He took Gouker's off-hand comments, combined them with his own resentment, and put it all on Trey. Trey was, unfortunately, connected to everything -- Terry, Amanda, Gouker, and all of that mess. All of the things that bothered Little Josh. He was the connection, even though he had no idea he was hated by Little Josh.