Characterization is simply defined as a description of the distinctive nature or features of someone or something or the creation or construction of a fictional character. A character gains life and personhood after creation and therefore has certain capacities or attributes such as age, morals, opinions and views, complexion, goals, philosophy, society, strengths, weaknesses, self consciousness, religion, gender, level of education, profession, cultures and ethnicities.
Each of the attributes above diachronically affect and moulds the individuality of a character. How a character speaks or thinks wholly depends on them. They are essential ingredients in coming up with the vocabulary for a character’s dialogue. If you create a dialogue without referencing them, you would basically be doing the equivalent of opting to draw a circle without an outline which is literally the only thing that defines it.
Henceforth, note that the attribution of a character will give you both the building and chopping blocks to create and eliminate certain aspects of their dialogues based solely on their attributes i.e. If a character has an extroverted personality, he/she/they are most likely going to be full of trivial conversation, carefree and loquacious as compared to an introverted one who is more careful in his wording, concise and uses sign language to further put his points across. The culture, society and ethnicity of a character has a direct effect on their dialect vernacular i.e. 38
the African American middle class' vernacular English is largely as a result of the sociolinguistic continuum.
Therefore to avoid the problem of your characters sounding the same in dialogue, #1. You have to ensure that they differ in certain attributes if not all. If they are identical in most attributes, make them lean more on the different attributes of themselves that make them stand out such as different tastes in art, songs and movies, hobbies, opinions etcetera. Do not just simply develop a character as a support beam for the main protagonist or antagonist.
#2. Create a hierarchy in power, personality, rationality, self consciousness, morality, experience or even age when writing dialogues to determine which character will be more dominant in regards to a certain topic or situation.
#3. If you can’t find a way to make a character’s dialogue different, you could try equipping them with a certain motif or catchword that they love to say or talk about. Like The Wire did with <PERSON>, a corrupt Maryland State Senator with a reputation for pocketing bribes. Unlike every other corrupt official, his dialogue stood out for his idiosyncratic profanity where he would comically elongate the word shit as sheeeeeeeee-it whenever he was confronted with bad news.
That is all. 425