While East-West relations have always figured strongly in studies of the Russian and Ottoman empires, the exchanges between Moscow and Istanbul, and the interactions in the borderlands that separated the two states, remain a fascinating but little studied field in world history. To uncover the complex relationship between the two empires, that since the early modern period have conveniently been lumped together by Europeans as their composite oriental counterpart, I propose a comparative study of diplomatic practice between these ‘Easts’. The focus of the case study is on the first Russian permanent embassy in Istanbul at the turn to the 18th century and the transition from ad-hoc missions to residence diplomacy. It investigates the religious, legal, political, and social norms that reveal themselves in the encounter of two empires that derived their claims to universal monarchy from two different religions, but that were also deeply entangled because of the multi-confessional composition of their populations, trade interests in the wider Black Sea region, and diplomacy. It dissects the life-worlds of the ambassador, his secretaries, translators, trans-imperial mediators, and their contacts with Christian Orthodox institutions in the Ottoman Empire. The study tells a history of empires from the vantage point of a Russian ambassador who resided on the Bosporus but whose trans-imperial network of intermediaries spanned most of EurAsia.