I had been familiar with the correspondence between Patriarch Jeremias of Constantinople and the early Reformers of Tübingen, but still found
this paper on the subject fascinating. Check it out. I hadn't known, for instance, that the Reformers actually sent a kind of "embassy" to Constantinople, or that they drew up a Greek version of the Augsburg Confession that was not just a translation, but an earnest attempt to communicate Reformation concepts to the Greek and Orthodox mind.