His stepfather spanked him, he had been a very bad boy

I would not say that the boy was bad, maybe a little perverted when he took his stepfather's underwear to jerk off with it. but let's see, it is also understandable with how good the mature man is. imagine the temptation to have it at home every day, it should not be easy. when he caught him, it was not that he was very pissed off, those spankings seem more like the beginning of a fuck than a punishment as such.