The term "bend sinister" means a heraldic bar or band drawn from the left side (and popularly, but incorrectly, supposed to denote bastardy). This choice of title was an attempt to suggest an outline broken by refraction, a distortion in the mirror of being, a wrong turn taken by life, a sinistral and sinister world. The title's drawback is that a solemn reader looking for "general ideas" or "human interest" (which is much the same thing) in a novel may be led to look for them in this one.
Vladimir NabokovAs far as I can recall, the initial shiver of inspiration [for Lolita] was somehow prompted by a newspaper story about an ape in the Jardin des Plantes, who, after months of coaxing by a scientist, produced the first drawing ever charcoaled by an animal: this sketch showed the bars of the poor creature's cage.
Vladimir NabokovWe all have such fateful objects -- it may be a recurrent landscape in one case, a number in another -- carefully chosen by the gods to attract events of specific significance for us: here shall John always stumble; there shall Jane's heart always break.
Vladimir Nabokov