Over the course of Carol Reed's "The Third Man", Holly Martins evolves greatly as a character as he begins to uncover the truths of Harry Lime's mysterious death. Holly arrives in a divided Vienna with a devout loyalty to his childhood friend Harry Lime. When he first hears the news of Harry's death, he is deeply distraught, but immediately attends the funeral. Martins refuses to accept Lime's death at face value. Though Major Calloway encourages him to leave Vienna in their initial conversations, Martins persistently continues to snoop around Vienna and interrogate different sources. Martins' strong devotion to uncover the truth behind these suspicious circumstances highlights his faithfulness to Harry Lime as a friend. It's clear that nothing will stop Martins from finding closure for his friend, but as the pieces come together, the story becomes more complicated than it first seemed. Holly hears of a third man present at the scene of Lime's death, and commits to discovering his identity. Eventually, Calloway and the police dig up Harry's grave, only to find a different man's body. After Martins finds out, he travels to the Russian sector to try to locate his friend. Again, Holly's dedication proves to be unmatched, as traveling between sectors could be complicated and even dangerous. Tensions between the former allies and the rising Soviet Union were beginning to rise, and spies were especially vulnerable. Though he doesn't find Harry, he demands a meeting at the local fair. When the two old companions finally meet, Harry reveals his sinister plans and lack of remorse.
Holly's feelings towards Lime begin to shift after he's threatened on the ferris wheel. It's clear that Harry planned on killing Martins, but chooses not to when Holly reveals the authorities dug up his grave and found a different man. Holly begins to realize that he is not dealing with the same friend he had as a child, but struggles to be the one to rat out his friend. Eventually, he agrees to help the police find Harry in exchange for help protecting Anna from the Russians. This represents a shift in Holly's feelings, as it becomes the first instance in which he chooses to put someone else before Harry. As the rest of the film plays out, Holly's sympathy for Lime continues to whittle away until the thrilling penultimate scene.
"Best friend I ever had" - Holly Martins
At the story's end, Holly reflects on the total transformation of Lime as a character. Martins also becomes a dynamic character, as his goal shifts from protecting his childhood friend to finding justice. Holly shares this explicitly by fondly recounting the memories from their childhood, and completes his radical transfiguration by eventually shooting Lime to end the film.