Tim Meeker is the main character of My Brother Sam is Dead. When the story starts, Tim is still a child. He admires his brother, Sam, and looks up to his father. By the end of the story, both his father and brother are dead, and Tim has matured to be the head of the household. The cause of both Tim’s growth and the death of his family members is the Revolutionary War, which is an essential part of the novel’s plot.

In the first chapter of the novel, we learn about Tim’s viewpoint by seeing the way he admires his brother’s choice to enlist in the revolutionary army. Tim views the war as glamorous and even explains that he wants to be a part of the action:

I couldn’t take my eyes off him; he looked so brave. He was wearing a scarlet coat with silver buttons and a white vest and black leggings halfway up to his knees. Oh, I envied him.

The envy that Tim feels is a part of his understanding of war and being a soldier. Tim is naive and doesn’t yet understand the horrors of war or its costs; however, by the end of the story, he has experienced the worst that war has to offer, and his views change and mature. Tim grows out of his envy, instead, understanding his father’s viewpoint about the cost and horrors of war. In the first chapter, he hears his father tell Sam,

You may know the principle, Sam, but I know war. Have you ever seen a dear friend lying in the grass with the top of his skull off and his brains sliding out of them like wet oats? Have you ever looked into the eyes of a man with his throat cut and the blood pouring out between his fingers, knowing there was nothing he could do, in five minutes he would be dead, yet still trying to beg for grace and not being able because his windpipe was cut in two?...Sam, it isn’t worth it.

During the war, Tim watches as the rebels harass his parents and kidnap his father, and the British kill his neighbors and friends. Seeing the horrors of the war takes the sheen off of his initial impression. The final nail in the coffin is watching his brother unjustly executed by the rebels. At the end of the novel, Tim reflects,

Perhaps on some other anniversary of the United States somebody will read this and see what the cost has been. Father said, "In war the dead pay the debts of the living," and they have paid us well. But somehow, even fifty years later, I keep thinking that there might have been another way, besides war, to achieve the same end.

Tim’s reflection on the costs of the war shows how deeply he has changed in the years since, but it also shows how he grew throughout the conflict. He sees the debt the dead, including his father and brother, have paid, and understands how costly the entire war has been. Tim’s growth, from innocence to adulthood, makes this a coming-of-age story.

I think the key to really understanding Tim Meeker's change comes through reading the novel's epilogue. In this final chapter, Tim is a 64-year-old man, and he is reflecting on everything that has just been told to readers. Having the advantage of hindsight allows Tim to really examine himself and the war. At the war's start, Tim is indecisive. He simply doesn't know which side to support, and Betsy even calls him out on it.

Then Betsy Read said, "Timmy are you on your father's side or Sam's?"

I wished she hadn't asked me that question. I didn't want to answer it; in fact, I didn't know how to answer it.

While Tim might not know which side to support, he does chafe a bit at not being able to participate like his brother. Tim's idea of soldiering and war is rose-tinted. He thinks war is glorious, and he believes being a soldier is a wonderfully brave and awesome thing to be; however, by the novel's conclusion, he no longer thinks that. War is what killed his brother and destroyed his mother on an emotional level. Tim does admit that the country he now lives in is great, but he does question whether the war was necessary at all. He no longer sees any glory in it.

But somehow, even fifty years later, I keep thinking that there might have been another way, beside the war, to achieve the same end.

Tim grows as a character from blind faith in his father and the Revolution into a teenager who is more in touch with his father's failings and the reality of the war.

Here is an excerpt from here at eNotes that should help you understand the progress of the character. You can learn more about Tim, Sam, and Life Meeker as well as other literary elements by visiting the link below.

"Fourteen-year-old Tim Meeker idolizes both his brother and his father. Tim narrates the story, and this perspective allows the reader to observe his initial innocence and his eventual perception of reality. Torn between his love for Sam and his loyalty to Life, Tim resists choosing sides. His desire to attend to the everyday concerns of his family, even during wartime, makes him highly believable. His character changes with time, especially as he recognizes that his youth does not make him inferior to his older brother. Tim quickly grows to maturity by taking charge of family responsibilities, unlike Sam, who abandons the family to fight for self-glorification."