For a long time, Europe was the land of kings and emperors. Monarchies and family dynasties ruled for generations, complete with their own alliances and rivalries that spread across the continent. While some of them still exist today, two destructive world wars and several democratic revolutions overthrew most of these ruling dynasties across Europe, leaving many rulers in exile. Today, most modern heirs to the thrones of European countries have the good sense to leave their claim alone... but some just can't seem to let it go.
Political revolutions, coups, and family rivalries have all taken place in the last few decades in several countries that had long deposed their kings and queens. Even the rise of communism in Eastern Europe and then the fall of the Iron Curtain wasn't enough to dissuade some nobles from biding their time and waiting for the perfect moment to take back their titles. Even today, exiled rulers of countries that changed governments during World War II still exist... and they even have loyal supporters who want them to reclaim their titles.