By the time Hannah is born, Louise has already held her countless times. For hundreds of those times, thousands, Hannah is an infant, a toddler, a little girl crying over a nightmare or skinned knee; for a few dozen more, she's a teenager who's just had her heart broken by her best friend, who'll stop speaking to her at fifteen for reasons unknown (and Louise will never be quite able to pretend to like Rachel, even when she and Hannah first meet, when they're both in the second grade and that betrayal is so far in the future); for a few hundred more after that, Hannah's sick, and Louise will be there for her every moment she can be, even in those weeks after Louise admits just how long she's known, and Hannah, like Ian before her, tells her she made the wrong decision.
As it turns out, speaking and dreaming and thinking the heptapods' language doesn't change one very vital thing about humans: regardless of the order in which we live our lives, it's the present that is the most true to us. It's the present that's the most real. And in the first moments of Hannah's life, as she lays on Louise's chest, this small person she already knows so well and is meeting for the first time, Louise decides—
It's one thing, if she tries to change what's coming and she can't. It's one thing if she gives it her all and loses Hannah anyway. But it's something else entirely if she gives up now, just because she's already seen Hannah die twice, already visited her grave half a dozen times while wishing it were as likely to go back as it always has been to go forward—
Louise has seen the future. She knows the name of Hannah's disease, all the things the doctors tried. She knows, too, that by the time Hannah dies, there will be treatments that could have helped, if they'd been developed a few years earlier, if they'd been available at the first symptoms.
There will be treatments, and Louise lives so much of her life in the future: It's not hard, once she knows what she's looking for, to figure out the details, an active ingredient here, a researcher's name there. And it's not hard to get people to listen to her, once they realize who she is, and especially not once they realize her information is always right.
By the time Hannah is ten, the treatments her future doctors thought might have helped are already saving other people's children—and when Louise visits the future, it's other treatments she hears about, even greater advances. She brings that information back too, hoping against hope that each piece will be the last one they need to make sense of it, to reverse the time bomb that's been ticking down ever since Hannah was conceived.
When Hannah's twelve, there's a strange patch. Louise's seen her in the future, so many times—but for a three-month period, she finds herself solidly planted in the present. She didn't realize how used she was to holding Hannah when she's nineteen and so, so sick, until she sits up night after night, aching with the need to offer that comfort.
When the first new vision comes, Louise thinks it's a dream, and a cruel one: Hannah, thin and pale, older than she's ever been, older than she'll ever be, and she's saying, "I've been thinking about going to grad school. What do you think?" Whatever Louise's answer will be, she slips out of it before she hears it, and wakes up crying, falling apart in the dark of her room the way she'll never let herself fall where Hannah can see.
When the second vision comes, not long after she gets out of bed the next morning, it's another flash, a bare few moments before it's gone: Hannah in a white dress, standing next to Rachel, the both of them laughing, looking at each other the way Ian used to look at Louise, a love that cannot be mistaken for anything else.
In the third vision, an hour later, there's a little girl, another child Louise doesn't know, and she's saying, "Nana, if I get a puppy can you keep it here?" and Hannah, somewhere unseen, says, "What did we tell you? Nana doesn't want to hear about that!" and the girl says "But Mom," and Rachel, also unseen, says, "Keeping a puppy here isn't going to magically make you not break out in hives whenever we visit," and Louise thinks about how refreshing and how beautiful it is, that they don't have anything worse to worry about at that moment than a little girl's allergies.
In the fourth, that afternoon, Louise steps into a hospital room, one subtly different from any of the ones she remembers. Hannah's in bed, visibly sick; Rachel's sitting in the chair by the bed, leaning forward, holding Hannah's hand, speaking earnestly. They're both crying, and although a moment before Louise would have driven Rachel out of that room, now she remembers the way they'll be, a few years from now, and she goes to get a cup of coffee, instead.
In the next week, Louise has a hundred more visions, each of them a part of Hannah's life no one has yet seen, a secret no one but she yet knows. Every time leaves her weeping, unwilling and unable to tell Hannah what is wrong—for she's never told her what's coming, though she would have, a few years from now. She would have asked her, near the end, whether she'd have preferred not to know; Hannah would have said no, that knowing was better than being lied to, being told it would be all right when there was never any chance that it would be.
A few years after the new visions start, Hannah becomes sick in the present. By then, Louise has seen her in her thirties, in her forties, her fifties; she's seen Hannah with gray in her hair, crying at her own daughter's graduation. Ever since the new visions started, she has never seen Hannah die, has never been to that grave; they are things that exist now only in past and memory.
At that first doctor's visit, and ever after, Louise holds her daughter, as she always has, and promises that everything will be fine.