How does the author elicit the empathy of the readers toward the main character Dickie? Does she use synxtax or diction to do so? Are the same techniques used in other novels to create empathy toward other characters?

Highsmith begins many of the sentences in which she discusses Dickie with the word "Dickie," emphasizing Dickie's agency and buoyancy. For example, when Tom Ripley first meets up with Dickie and Marge in Italy, Highsmith writes, "Dickie and the girl went out quite far—both seemed to be excellent swimmers" (49). A later sentence begins, "Dickie and Marge went in front of him, taking the endless flights of stone steps slowly and steadily, two at a time" (49). In this sentence, Dickie appears first syntactically and in actuality, as he is able to bound up the steps before Tom. In the next sentence, Highsmith writes, "The sun had enervated Tom." Unlike the sentences in which Dickie appears first as the subject of the sentence, Tom appears last in this sentence and is the object of the sentence. Being the subject of the sentence makes Dickie seem more powerful and likable, while being the object of the sentence makes Tom seem weaker and less likable. The author's use of syntax and diction (such as the use of the word "enervated," or worn out, to describe Tom) emphasizes Dickie's power and ebullience and Tom's weakness and lethargy. Later sentences also emphasize Dickie's energy—for example, "Dickie turned his fork round and round and thrust a neat mass of spaghetti into his mouth" (51). Even while eating pasta, Dickie makes movements that cause him to seem virile and worthy, while Tom is constantly described as weak or enervated. The word "thrust" in this sentence particularly emphasizes Dickie's virility.
While the pronoun "he" is used often for Tom, Dickie is most often referred to with his name, and Highsmith constantly inserts Dickie's name into the text. As a result, the name "Dickie" appears quite often in some sections of the book. For example, in the following excerpt, "Dickie" appears twice in a row: "He was waiting for something profound and original from Dickie. Dickie was handsome" (65). The repetition of his name also makes Dickie appear strong and makes the reader like him. These techniques are also used in other novels; perhaps you can find examples of them in some of the other novels you have read recently.