A foreign man
Why is Humbert foreign? Is Nabokov writing about his own migratory experiences? Did he go to the USA? (I know nothing about him and I have no internet access.) Is his foreignness a cypher for his child-loving difference?
He is nebulously foreign to the Americans. He is from Switzerland, a land of five official languages. He has an odd accent and mannerisms. Mostly this is romantic, but sometimes it is less clean than American life demands: 'Shrugged my shoulders. A shabby émigré.' In fact, I sometimes forget he is foreign, and the picture of him I see strongest is someone private, someone of books and learning amongst philistines. This clarifies to me his claim to be a of a poetic nature: perhaps he takes his love of pubescent girls to be a rarefied form of sexual appreciation. He certainly seems to lust and desire in an extravagence proportional to his intellect.
He is foreign in language, culture, mannerisms, nationality and lusts. He looks in from the outside in all things and this makes for a fascinating novel.