I don't think we can say he's raping him. He's waking up mid-scenario, fully dressed and still in the same position. And no indication that there's any drugs - the kid doesn't drink something regularly or whatever.
Whispering in his ear, maybe, to put those dreams there.
That last chapter was creepy.
That tutor is such a predetor, raping that guy in his sleep and making the him confused about what was going on.