ilojaofprim:

“[Michael Piller] was always looking for the moral angle, the emotional journey, the dilemma,” Biller says. “My original draft ended with them splitting Tuvix, him saying something very Starfleet about sacrifice, and Janeway was off the hook. Michael’s note was, ‘Make him fight for his life.’”

So Biller rewrote the script with the mandate that Tuvix was a new person, an individual. Janeway would decide whether to execute him. She settles on returning Neelix and Tuvok to their original selves, and in the final minutes of the episode, after begging for his future, Tuvix is suddenly gone.

“Much like the episode itself,” Biller says, “the making of the episode had an arc. It began silly […] then turned into something dark and even profound. I mean, what could Janeway do? What would you do?” - Polygon.com