But 99% of the time you don't know the author's intentions, especially for non-contemporary works.
Except that sometimes the text itself makes it pretty clear that intentions have changed. "Q Who" explicitly stated that the Borg are only interested in technology and ignore people. BOBW had the Borg assimilate Picard and explicitly stated that it was a special case. But by VGR, assimilating people was portrayed as their default practice. You don't need to know a thing about underlying intent, it's right there in the text, as explicitly as James R. Kirk versus James T. Kirk. We are, after all, talking about different authors adapting the same concept to suit their needs, so of course the intent changed.