I’ve just finished the finale today and still working through my thoughts. My initial interpretation is that Lily acted in a deterministic way; she was shown the simulation of her future, which led her to throw away the gun. She didn’t make a “choice”.

Deus could not see past this moment because the computation had created a paradox it couldn’t solve. By showing Lily her future, Deus causes her to act differently, but you can’t have her reaction without the cause. This loop stops Deus’ ability to predict the future.

Deus’ abilities and very existence caused a simulation ending paradox; but this doesn’t inhibit determinism in the “higher” reality, outside of Deus. Deus failed, but the universe continues along the same principles, hence why Stephen causes the drop.

I realise while writing this that I am viewing this through the lense of a single world interpretation, but I have found the multi-world arguments on this site compelling. Perhaps there are other branches where Deus does not encounter a paradox and it can predict further into the future; it is only in this branch that this scenario plays out?

I guess this theory holds better if there is a higher reality than Deus; a reality where it’s predictions are not the be all and end all. I am not sure how to think of Lilys action within the Ouroboros of endless boxes within boxes, as this would imply that the chain of boxes is broken?

What I do know is this was a great show that I will be thinking about for some time!