Currently writing an essay about the Islamic-Christian attitudes toward one another during the early Crusades, specifically how their wrong beliefs about the opposition's faith and values might or might not have been the straw that broke the camel's back. In Western Christianity you've got this growing warrior class of nobles constrained by scarce land and money, fighting each other over and over again, but mostly chasing tails. In Eastern Islam you've got the people who kept Greek thought alive while the West lost all literacy and intelligence, and a people group who were the trading center of the whole Old World, wanting to expand their trade and develop their wealth and influence to the people of the West who spent their time chasing tails.
The original texts written by Muslims and Christians of that era are surprising. The Christians actually seem pretty superstitious and backwards and they do weird things in the name of God like having a boat load of prostitutes shipped to the Holy Land to provide the crusaders with necessary services of all sorts. You also hear these stories about women dressing themselves up like men to fight and older women acting like busybodies around town. Very weird. The Muslims seem snooty but are admittedly much more sophisticated in science, math and medicine because they didn't go through the same "Dark Age" period where learning was snuffed out, so they've got this attitude toward the Westerners that is like a teenager smirking at his five year old brother for wearing a towel around his neck and calling himself a warrior. The crusaders come off as zealous and ardent in a way that makes a modern Christian cringe, whereas the jihadists are lucky enough to come off as rational but simply repulsed by the crusaders.
Any number of theses could work for this essay, but of course, I'm looking for the perfect golden scarab hiding under an amethyst rock. I think that the fact that these original eyewitness accounts of the crusades are so surprising to me is a great start. Curiosity is always a better fuel than boredom for these sorts of things.