Yeah, this recent chapter he seems to be picking up that his son is a separate entity from his wife and there is now an idea in front of him that his son may be a bigger victim than himself.
Honestly, the easiest way to absolve Rishar is for Etienne to tell his father about being drugged his whole life and spinning the situation as asking Rishar for help as an alpha so he can get off his medication. It would immediately take the blame off of Rishar and permanently take Etienne out of the runningfor the throne. The empress can't kill all three of them.
But Etienne won't do that because it would tie Rishar to him and he doesn't believe Rishar looks at him that way (or that he deserves that kind of attention.) We, as the audience, know that this lines up with Rishar's ideal situation; he 100% wants to be with Etienne.
But he will come around, and in an important way too. (⌒▽⌒)