In re-watching season two of Grimm, I've noticed how frequently Captain Renard goes to his office to talk on his secret phone in French. At first this struck me as kind of odd because so much of the show has to do with things that have their origin in Germany or at least German-speaking places (Vienna starts becoming more significant in season two). But then I realized that he speaks French because he's a Royal.
I recently re-read my textbook (A Concise History of Modern Europe) for the class I took on the History of Modern Europe, and the author (David S. Mason) mentions that "French culture was admired and mimicked by the upper classes throughout Europe, and French was the language of the aristocracy and royal courts all over the Continent, including in Russia." Later in the book he writes that "French was the most widely used international language, the language both of diplomacy and of most of the royal courts of Europe."
Since Renard is a Royal, he still uses French when he's dealing with those sorts of aristocratic and royal issues. I'd thought that his use of French was just an-other way to conceal what he's doing, but it also has historical precedent.
