This is an intriguing question. For your purposes, treating Humbert as the victim of his perverse nature and ideas may be easier as you may be better able to find more "evidence" to support this thesis. For, he seems more driven by his nature, driven to devise a way to be near the girl by marrying the mother, yet it is Lolita who initiates the lovemaking at the motel. Later, in Chapter 19 Humbert reflects, "I have often wondered why she did not go for ever that day.... Was it some unripe particle in some general plan?" It seems at times that Humbert feels a sense of fate in his relationship with Lolita.