Paul Baumer is of course the protagonist and narrator of this incredible war-time novel, and through him the author voices his own ideas and opinions about the war. His major importance consists in the internal conflict that Paul has between his inner character and the kind of exterior character that the war forces him to adopt. His gradual change as a result, which is highlighted by the flashbacks to his character before the war, show how war changes those involved in it. As the novel progresses, the young, tender and sensitive man who wrote poetry and loved his family more and more deeply is forced to disconnect his mind and ignore his feelings so as to help maintain his fragile hold on his sanity.
Some of the changes that we see is that Paul finds it impossible to mourn his dead friends and is extremely ill at ease when he is with his family. He becomes incredibly repressed as he can't express what he has gone through and finds it difficult to imagine a future without the state of war. The novel also describes him as a "human animal" as he comes to increasingly rely on instinct to survive. However, Paul's sensitivity causes him to find it difficult to completely detach himself, and the novel includes a few key moments when emotions threaten to overcome his detachment, such as when Kat dies, when he is with his mother and the death of Kemmerich. These moments however only serve to highlight the way in which war has forced Paul to become detached. Note for example his comment on Albert Kropp:
Parting from my friend Albert Kropp was very hard. But a man gets used to that sort of thing in the army.
Such devastating understatement only serves to reinforce the changes that war has wrought in Paul's character. Paul's death at the end of the novel is ironically something of a relief as we begin to wonder how on earth he will return to normal life. However, the novel shows that the war had "killed" Paul's character long before he actually died.