Jonah switches bodies from James to Elias without bothering telling to Peter that he even can do that. He is curious if Peter cared about him as James and also if he can figure out his identity based only on hints he will give him.
However Jonah’s hints are not subtle at all plus he has the same Beholding bastard energy so Peter realizes that Elias and James are the same person almost immediately.
But Peter decides to play along with his game anyway. He pretends that he has no idea about his identity and that he actually didn’t even like James.
So in the end Jonah is the one who takes embarrassingly long to realize that Peter is not that dense and that he’s the one who’s playing him and not the other way around…