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How does what comes after the reveal relate to what went before? If their newfound understanding makes their past lives irrelevant to your protagonists, then it will become irrelevant to the reader...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/32710 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
How does what comes after the reveal relate to what went before? If their newfound understanding makes their past lives irrelevant to your protagonists, then it will become irrelevant to the readers, too. Make sure that the plot is driven by some continuing concern or goal or task of the protagonists that connects the before and after parts of your novel. For example, if the detective learns halfway through the novel that his suspect is in fact innocent and he has to start from scratch, that does not make his attempt to solve the murder mystery vain. On the contrary, readers will empathize with his frustration and their curiosity over "whodunnit" will be kindled anew. So just as an example lets assume that your protagonists are dealing with typically teen worries about love and parents and school. Now they know they aren't human, but does that change anything for them? Not really. They still have the same desires, fears, and emotions, they still want to be loved and succeed at life. That all that goes on in them is not a result of evolution or the hand of God, as it is in a human being, but a result of clever programming, does not change what they want from life one single bit (or byte, lol). It does give them a different perspective, and that change should affect them somehow, but it is no different than a priest losing faith: just like your AIs learn that they are not natural, the priest learns that he is natural and not created – both have to overcome their spiritual crisis and learn that it is irrelevant to how they need to lead their lives. All books are about a change of perspective in one way or another. Your plot twist is highly intriguing, and I don't see how it must necessarily break your narrative, if you handle it well.