This is a fairly straightforward question, alluding to the final line of the first paragraph of the story:
“And every time we saw her on the screen, right behind her was Rolf Carlé, who had gone there on assignment, never suspecting that he would find a fragment of his past, lost thirty years before.”
Foreshadowing is a literary device in which an author hints at events that will occur later on in a narrative – here, Allende gives the reader a hint at Carlé’s transformation over the course of the story. This particular line makes us aware that Rolf’s time spent with Azucena will awaken memories of his own life at her age. In addition, his struggle to keep her happy during the last days of her life, and his obstinate denial that they are indeed the last days of her life, will forever change him – it will draw him closer to an understanding of himself, of how and why he became the man he is.
Near the end of the story the narrator confirms this suggestion as she watches the story unfold on the news:
“On the evening news broadcast, he was still in the same position; and I, glued to the screen like a fortuneteller to her crystal ball, could tell that something fundamental had changed in him. I knew somehow that during the night his defenses had crumbled and he had given in to grief; finally he was vulnerable. The girl had touched a part of him that he himself had no access to, a part he had never shared with me. Rolf had wanted to console her, but it was Azucena who had given him consolation.”
As he told Azucena stories of his own life and fairy tales from his homeland, the memory of old traumas and broken relationships flooded back to him in an overwhelming tide. Things that he had forcibly forgotten were remembered, and he realized that his own occupation as a reporter was merely a way to distance himself from the intense drama of living, to hide behind a camera lens and view the world once-removed. These realizations and recollections brought on by his desperate relationship with Azucena forced the transformation foreshadowed in the first paragraph, and establish him as a dynamic character; the persona he has created to shield himself from the past becomes a secondary casualty amid the fallout of the catastrophic earthquake that serves as the setting for the story.