Again, I think that’s a simple rule to follow. If the character knows something important to the reader, then the reader should know it. Notice in the opening of the “Little Magpie” story that the character tells the reader right away what’s at stake: they’ve had early miscarriages and Maggie is pregnant again. He doesn’t hide that information. What he doesn’t know is what he should do to make sure this baby lives, what he should do to help Maggie not have another miscarriage. His trying to figure that out is what the story is about, and he shares that process of figuring it out with the reader.
The twist ending attracts a lot of flash writers, and the “twist” often occurs by hiding information that the character/narrator knows but doesn’t what to reveal yet because it will ruin the “twist.” But Almond argues, and I think correctly, that the reader feels like some trust-bond has been broken when writers manipulate them in this way. Notice that the famous twist of Sixth Sense follows Almond’s rule because the character doesn’t know the truth until the very end. If indeed the character of Decker is a replicant in Blade Runner, then that twist also follows that rule, as Decker doesn’t not know he is a replicant until, perhaps, he sees the origami unicorn at the film’s end, the one that he thought only belonged to his subconsciousness.
I think it is important to find a way to “twist” expectations so readers are engaged. And it’s important to think about what’s holding their interest, what they’re waiting to find out. The question for me is this: How will they be surprised without being tricked, without feeling like what they’d should’ve been told has been withheld from them, unjustly?