You Reap What You Sow, Big Brother
Out of all the empires in history, the Romans were one of Berengar's favorite. What they accomplished inspired numerous men to achieve a level of greatness similar to their own, yet few had ever succeeded in matching the glory of the Roman Empire.
The Byzantines were technically the surviving Eastern half of the Roman Empire after being split in two by Diocletian during the formation of his tetrarchy. In reality, by this point in history, the Byzantines were far more Greek than Roman.
Despite this, they still referred to themselves as Romans and touted the ancient lineage of Rome as their own. Much of its nobility spoke Latin as a secondary language, which was the primary reason why Berengar was able to communicate with Honoria during their first meeting so effectively.