OK, this is the story of a grown man and a thirteen-year-old girl, so you might be alarmed to see "Love" as one of the themes. However, don't flip your wig – this isn't Lolita, and we're certainly not talking about romantic love here. No, instead we're talking about other kinds of love – for example, familial love, friendship, even a hint of bromance. Love, says "For Esmé," comes in all different kinds, and all of it is productive. This is a story of simple human connection, and what a fundamental impact it can have on a life, even in the darkest of times.
The one thing that keeps Esmé going is her abiding love for her father; this love is the source of her strength.
The narrator's own life is possibly devoid of real love, yet he is inspired by Esmé's capacity for it – though she herself is concerned about her coldness, he sees that she truly loves her family, and this ability to love is what makes her so compelling.