Lessons From The Future by Grey Wolf
The idea that a leader from the past could be transported to the present (his future) and then returned with knowledge is a staple of science fiction⁄alternate history crossover, but I always felt people misunderstood the lessons they would learn.
We assume they would learn lessons about kingship and the facile nature of royalty, that war does not gain them anything, that hopes and aspirations of honour and power are mere chimera. We assume this because history tells us this about their reigns, their power, their progeny, their dynasties, their countries.
But history does not tell us this about power, about war, about money, or about bloodlines. We assume they would take a narrow lesson when the broad lesson tells something different. That is us, projecting what we like to think of our values back upon the past, but the past has eternal values, it would learn eternal lessons.
A king from the past presented with evidence of his eventual failure, the extinction of his dynasty, the loss of all of his territorial claims, the hopes for his country's future, would not learn a lesson of humility, but of victory. He would look at why he lost, how he lost, where he failed, what he should have done better.
But the people of the present who would tell him that the lesson he should learn is one of hubris, humility, etc fail to understand that history teaches the opposite. Kings may fall, royal dynasties may collapse, empires may disintegrate, and ambition may be crushed, but the rich, the powerful are still amongst us in families, dynasties, trusts, and politics. Any intelligent being would look at this.
And what lessons could be learned? That power and money should never be divided. That the sources of money will change over time, but you need to keep a hold on it, and diversify. That society will always bow to money even when it does not to power and privelege.
Perhaps even they will learn that soft power can suborn hard power. That anyone with the ability to lend money, or finance investment, can trump the so-called rulers of a realm.
But the lesson they will NOT learn, is that they should not try, not bother, not attack, not destroy, not conquer. It will simply be that they should do it better, in different ways, and they will learn those ways and apply them to their own time.