Poets never kill
Humbert Humbert claims his kind are essentially harmless:
We are not sex-fiends! We do not rape as good soldiers do. We are unhappy, mild, dog-eyed gentlemen. [...] Emphatically, no killers are we. Poets never kill.
Later, he upbraids Charlotte for exerting such control over his life, and she is very contrite:
She said I must forgive her, or she would die. This little incident filled me with considerable elation.
Obviously Charlotte is exagerating, but the juxtaposition of death right at the end of that sentence and it running immediately into one about his elation cannot be coincidental. Possibly this is just mild foreshadowing but it seems a bit more sinister than that because of course she does die, the top of her skull is 'porridge', and he has to fake sadness. He didn't kill her directly but she read his journal and was rushing to post letters reflecting her new knowledge, and she might have looked both ways if she hadn't been so upset. She is dead because of him, but he remains a poet who doesn't kill. It's impossible to agree, not that we did anyway, that his kind are essentially harmless.