Interestingly, Laszlo was shown to have some interest in kinky stuff as early as the episode 4 of season 1 during his conversation with Mrs. Williams. I also got the impression that his relationship with Mary was somewhat kinky, and that Mary enjoyed the fact that he was so dependent on her in everyday tasks like tying his shoelaces, that she had some sort of control over him in spite of him being a famous alienist and her a nobody. Especially when she left him for the whole day and went with John to see the Edison expo, and he had to manage on his own (and the underwear-sniffing scene).

Perhaps, if Mary didn't die and their romance continued, it would have become more obvious, with Mary being subservient in public, but de facto dominant in private when there were just the two of them? (I even thought that the scene with Mrs. Williams and the brewery foreman, when she says that he is used to giving orders at his work, but prefers taking them at her house, could have been intended as a parallel).