Without that fact he could never stitch him up. Plus isn't angier a mass murderer?
Hes a nasty piece of work either way!
Plus did cutter (caine) know of the daily drownings?
I assumed that angrier knew because he could hear bale screaming for help to get angrier out of the drowning box so he did appear on the balcony but snuck of leaving bale looking like the murderer. He knew that bales character would eventually sneak his way down there to find out the secret.
But what about the old guy sitting in the chair. Did he get up and walk off or was he questioned?
Cane didn't know about the drownings as he wasn't allowed to go down to the bottom which he was fine with.
I assume that's why he did 100 shows. He drowned a duplicate in each show. He never knew which performance Borden would be present for so he had the frame ready to fit every night.
I think Angier recognizes Borden as he comes up on stage to check the machine. That's the only way the teleported Angier would know that he should avoid "the prestige" part of the act.
I think Cutter learns the whole truth only in the end. That's why, he tells him how drowning feels like.
Maybe it was the 100th show, and he had just anticipated it.
** Rest in peace, Timothy Volkert (1988 - 2003) **share