When in the writing of "The Expanse" book series did Abraham/Franck set the final outcome for Amos Burton?

Question

I've read through the entire Expanse series and now re-reading (just starting book 6).

In all the books I keep coming across people discussing Amos Burton as the guy you can always depend on to have your back, the guy who'll be "the last man standing".

Is there any input from the authors regarding when Amos' storyline was "set"?

EDIT: My question is primarily about the last paragraphs of the final book's epilog where it turns out Amos is the ultimate survivor.

Was this always in the authors' character arc plan for Amos from the very beginning or did it form up this way as the books moved along?

Answer 1

From the interviews I can find, it's appears that Amos' fate was planned by the end of Caliban's War.

This article talks about them planning options for the series based on what the publisher might agree to once the second novel was released (different lengths of the series), but notes that the same end scene was planned regardless of how long it took to get there.

On June 26, 2012, Caliban’s War hit bookstore shelves accompanied by more positive reviews, helped along by Corey’s able publicist at Orbit, Ellen Wright. From that point, Abraham and Franck began to plan ahead. The books were selling well, and Orbit was standing behind the series. They sat down and drew up pair of outlines, one with nine books, the other with twelve, each ending up in the same place. They picked their direction and ending, and figured out what would have to happen in the last installment, right down to the last scene and line, and what would have to happen in each book.

A further interview also describes the final scene being written during Caliban's War, but then refers to the main text rather than the epilogue:

The pair even knew Leviathan Falls’ last line — Naomi musing, “The stars are still there. We’ll find our own way back to them” — since they were writing the second book, Caliban’s War.

However it also includes a strong implication that Amos' fate was planned and intentionally foreshadowed early on:

In the epilogue, we learn that Amos is the one helping guide humanity through this next stage. Why was this the right place for him to land?

Abraham: We had him refer to himself as the last man standing really early in the series. […] He’s that combination of weird compassion and total lack of sentimentality that it just felt right. What a great place to grow to.