When "My Brother Sam is Dead" first opens, the audience sees Tim as a wide-eyed boy. He sees war and battles as this grand adventure and he is a little disappointed that Sam gets to enlist in the army without him. Throughout the story, Tim is constantly trying to prove himself and get a taste of what he thinks of as Sam's glorious life.
Once the war begins, however, Tim's reality is shaken. He sees soldiers enter his home and prepares to fight them off. Later, he sees his father get kidnapped and barely escapes with his life. Through these events, Tim learns that war is not an adventure but rather a brutal reality which costs many innocent lives.
Tim's vision of war changed so much from the start of the story that when Sam's time comes to re-enlist, Tim begs him not to. He knows it will make him seem weak or afraid, but he doesn't care. At that point, he just wants to keep his brother safe—ultimately to no avail.
At the very end of the story, in the epilogue, the reader gets a chance to see the adult Tim has become. He leads a happy and fulfilling life but still isn't sure the cost of war was worth it in the end.