The whole point is in characters' stats and traits. If you choose to value charity or honesty during one of your therapy sessions, you have to make as many choices that raise those stats as you can so Josh's friends could live up to his expectations, cuz if they don't Josh won't be sorry and will say that "they need to change". I'm not sure how exactly you need to act if choosing loyalty, but I think it is somehow related to other characters' sympathy for Josh.
Anyway, I recommend doing whatever it takes to "please" Josh no matter what you value the most, playing as kind as you can being nice to everyone and VERY IMPORTANT - being sorry about sisters' death every time characters mention it.

Besides, you also need to save all the other characters so Josh couldn't turn into wendigo.

And also you got to find Hannah's notes while you're in the cave as Sam together with Mike. Otherwise, Josh would not recognise his sister and would have his skull crushed.

I don't think any other collectibles matter, but just in case I collected all collectibles related to the Josh's "show", while playing as Ashley and Sam (have to escape from Josh earlier so he didn't catch you, allowing to explore the area where all the clues that reveal the personality of the killer are located) in chapter 6. All his cameras, plans, his phone, therapy report and other stuff like that. Those clues would lead to changed dialogues between characters. Ash and Chris would agree that something suspicious is going on and what's more important Sam would tell Josh that it was obvious who the killer was.



My 100% working strategy to obtain the "We need to talk about Josh" trophy

I started a brand new game on a new save slot.

On the therapy sessions I was following this guide:
I was raising charity of all the characters, was good to Josh and tried to save him instead of Ashley. Didn't hit him with the vase, the bat or scissors (I didn't even take them so Ashley didn't resist at all. I know this way you miss one of the clues, but it's fine). I was even able to tell Mike that it might be NOT Josh who "killed" Jessica while playing as Chris. I've never had that dialogue option before.

Just in case I collected all the clues related to Beth and Hannah while playing as Emily in chapter 7. She would tell her friends about them, but Josh would never know it, so I don't think it's necessary.

Didn't hurt any animal, saved the wolfie as Mike. Again, just in case.

And sure thing I saved everyone and found Hannah's notes in the last chapter for Josh to survive.



Let me know if this worked! Love y'all!