How I Live Now is Daisy's story, the story of how she, a sassy, jaded New York City teenager, came to be living happily in the post-war English countryside with her cousins, an incestuous lover, and a gaggle of farm animals.
We're warned ahead of time that Daisy's going to tell the story of how she got from Point A to Point B, which gives us the minor spoiler that she actually makes it to some Point B, and also lets us know that the voice we're hearing has the benefit of hindsight. And there are a few moments that Present-Day Daisy jumps in to remind us that this is a story she's telling us—"it would be easier to tell this story if it were all about […] but let's face it that would be a load of crap" (1.10.1)—and that she's telling it as truthfully as she can.
However, for the most part, Daisy shares her unedited thoughts as they arose in the moment, making us feel like we're right there with her, like when she writes, "I wondered quietly to myself What Was Happening Here but of course it doesn't matter how quietly you wonder things" (1.9.24). Did we mention she's kind of funny? Because she is—we totally don't mind hanging in her head.
At times, Daisy also gives us her current unadulterated thoughts on a situation, looking back on things after having lived through them. For instance: "In retrospect, I have to think it was the kind of connection that makes people decide to phone each other at the same instant after fifty years of not talking" (1.18.6). But whether she's giving us the benefit of her 20/20 hindsight or putting us in the moment itself, one thing's constant: Daisy is always running the show.