A number becomes personal for Finch. He doesn't share the details with John, but John figures out it's something to do with Nathan. Finch should know that where his needs are concerned, especially for something this vital, John's notions of boundaries become skewed.
So he shouldn't be surprised that, in order to stay on the inside, John is letting the wealthy older man behave in a creepy, inappropriate manner towards him.
When he finds out, he immediately goes and recovers John from the number, and totally destroys his world - more for what he did to John than what happened to Nathan (he tells himself it's justice he wants but when he realises what what was happening to John, he knows it was actually revenge and he doesn't mind).
Then he takes John to the library to look after him and tells John sternly that he no longer works for the CIA and he, Harold, will not expect John to prostitute himself for him EVER. If he has one thing he does expect from John it's to try and keep himself safe.
Reese/OMC, non-con/groping, protective comforting!Finch
So he shouldn't be surprised that, in order to stay on the inside, John is letting the wealthy older man behave in a creepy, inappropriate manner towards him.
When he finds out, he immediately goes and recovers John from the number, and totally destroys his world - more for what he did to John than what happened to Nathan (he tells himself it's justice he wants but when he realises what what was happening to John, he knows it was actually revenge and he doesn't mind).
Then he takes John to the library to look after him and tells John sternly that he no longer works for the CIA and he, Harold, will not expect John to prostitute himself for him EVER. If he has one thing he does expect from John it's to try and keep himself safe.
(Because he's Harold's world, now, you know).