From very early in the story, we are aware that Alex is obsessed with Henry. That obsession is demonstrated by a fixation on various photos of the prince. Alex tells no one that he’s kept a photo of Henry playing cricket. Initially, he can’t explain what it is that attracts him, but he keeps the picture anyway. Photos of Henry later have the opposite effect. They repel Alex. When he contemplates the prince looking picture-perfect, like a plastic doll, he grows angry. 

For his part, Henry has taken a mental snapshot of Alex during their first meeting at the Olympics. Years later, he describes in precise detail every aspect of Alex’s apparel and demeanor because it was the moment Henry fell in love. As their relationship progresses, the two men send phone snapshots to one another. As Henry allows Alex greater access to his psyche, he also allows himself to be photographed sleepy and rumpled. This is an indication that he’s grown more relaxed with the relationship and with himself. When the two participate in a formal courtship photoshoot, it is the candid photo of Henry and Alex having a laugh on a park bench that captures the essence of their relationship.