I think it's more complicated than that. I think they were both driven by pheromones but didn't force themselves to it. Yet, Chase is traumatized by the lies of his brother which might have causes him to forget. They were obviously both hazy but only Josh remembers because he has no prior trauma. Hope this was logical enough
Pretty sure Joshua was also intoxicated by chase pheromones. The only difference is Chase hold out on releasing his pheromones for so long,he doesn't remember what happened. It's really complicated if you think about it. If chase went into a rut then he probably was the one who jump on Joshua and Joshua consented it cus he like chase. Just like the chapter where Chase comes back from the party that Grayson took him too. He try to push him away but have up and let him kiss him because he is weak for him.

If Chase wasn’t conscious but Josh was … does that make it Josh is the rapist? Cuz ???? Yeah? No? Like can someone tell me using realistic logic?