The J. Irving Protagonist is the main character in the novel 'The Sun Also Rises' by Ernest Hemingway. The acronym TSGARP stands for the protagonist's full name, which is Theodor Sebastian Garp. He is a World War I veteran who is struggling to find his place in the world after the war. He is an American expatriate living in Paris and is surrounded by a group of friends who are also expatriates. He is a complex character who is trying to make sense of his life and the world around him.