That Cool Dialect on The Expanse Mashes Up 6 Languages
Belter is more than an accent. It's full-fledged language that speaks to outsiderness.
A great interview with Andrew Rotilio (he speaks four languages!), Nick Farmer, and Eric Armstrong (the dialog coach for the show, amazing job).
“To do that, Armstrong asked each actor to speak Belter with their own personal style. In Rotilio’s case, he used his Italian inflection. “The idea was that Belter would be consistently inconsistent,” Armstrong says. “But there are some anchor sounds that we are aiming toward regardless of how strong or weak an accent is. Like, in Belter ‘TH’ words frequently switch to a D sound, so ‘dat ting dere.’ But someone who is an extremely well-spoken Belter, we make sure they can hit those THs.” In this way, the different variations of Belter on the show are a strength, not a liability.”