There are some podcasts where the showrunners talk about it, its been a few years so not sure where I heard it. But mostly it just boiled down to usually 3 things
1 - less characters the better, so some were given dialogue and story beats from other chars. Drummer was merged with the book engineering hot shot
2 - they really, really liked some actors and meat-d up their roles. Ashford and Drummer are big examples of this
3 - moved some stuff around so characters would not be out of the show for long stretches of time, Bobby/Avasarala are prime examples but also Naomi's family stuff
some stuff was also just going to be too expensive to film like some of the big battle stuff cut out.
The show is already really expensive, amazon didn't increase the budgets that much when it transitioned from SyFy. A joke I remember from the podcast is that the shows nickname in the crew was "The Expense"
still crazy to me that only 6 episodes in the finale, that'll be interesting to hear about in the BTS podcasts. One of the creators, showrunners, and writers + the actor who plays Amos has a podcast that just kinda goes over random stuff and they are up to 35 episodes now (the apple, spotify, google, etc links have the full list while their website only has like 12)
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