When I signed, a lot of things were similar to the final rendering. We tested a lot of versions on the last act, but it was known that in the end, Ellie kills Abby. It was halfway through production that we changed that, and Ellie ends up dropping it, in order to show us that there’s a part of the old Ellie in her, the Ellie with her humanity, the Ellie who has. been influenced by Joel, this character still exists despite this mad desire for revenge.
This change of direction came when the writers discussed the fate of Lev and Yara, and they were not yet sure which one or the other should die or stay alive. It wasn’t until it was decided that Lev would stay alive that Neil Druckmann came up with this idea of letting Abby live, so Ellie couldn’t go through with her revenge. For Naughty Dog, it was the best decision possible and it also allowed to offer more possibilities and to leave the door open for a third episode.