The Expanse is set in the future, where humanity has colonized parts of our solar system, with communities on Earth, Luna (the moon), Mars, and on stations in the Asteroid Belt and Outer Planets. The characters who would speak the conlang on the show would be from this last area, members of the working class group known as “Belters,” who came from an extremely culturally diverse pool. Belters would speak “Belter” language, which would be unintelligible to outsiders. This language would be a Creole, made from a mosaic of source languages that included English as its “superstrate” language, but also “substrate” languages such as German, Spanish, Russian, Chinese, Arabic, Portuguese, Hebrew, Zulu, and Japanese, among others. As you may know, when languages of this nature evolve naturally, the first generation speaks what is called a Pidgin, while subsequent generations further develop and deepen the language into a Creole. This is what Belter was to be. Inventor Nick Farmer, an autodidact hyperpolyglot who works in the financial services field and speaks 14 languages, created a series of rules for the language, a grammar and phonology, that allowed him to draw words from any of the substrate languages and transform them into Belter words. In some ways, the phonology worked as a kind of filter, which would pull the phones of a source word apart, and then rebuild it with those that were part of the limited range of phones permitted within the new creole.