Tagmatium wrote:'bout Empress Irene marrying Charlemagne?
That'd be a very interesting alternate history.
Although she'd probably have got deposed, as shocking as marrying a barbarian was.
As you probably know, Irene did raise this issue - and it may well have been one of the primary reasons why she was deposed by Nicephorus I in 802, though the sources aren't clear on this, and it's particularly hard to separate truth from propaganda here given Irene's status as the first woman to rule the Roman Empire entirely in her own right.
But there's a better candidate for a historical 'what if' involving intermarriage between the Byzantines and the Holy Roman Empire....
What if Holy Roman Emperor Otto III, son of the Byzantine Princess Theophana (herself closely related to Byzantine Emperors John I Tzimisces and Romanus II - though it's not clear what the precise relationship was), hadn't died at the age of 22?
Theophana was an important influence on Otto - serving as his regent between 984 (when Otto was all of four years old) and her death in 991. Otto deliberately tried to introduce Byzantine court ceremonial into the Holy Roman Empire, and explicitly attempted to model his state on Byzantine theocratic ideal models. Otto died when his own Byzantine bride - almost certainly Zoe, daughter of Constantine VIII (see earlier posts) - had just landed in Italy to prepare for the wedding; which certainly would have changed Byzantine history, as well as German history if it had gone ahead.
But instead, Otto - who had died while attempting to crush an Italian rebellion against his rule - was succeeded by his cousin Henry II. Henry is the only Holy Roman Emperor to have subsequently been made a Catholic saint, so we have to assume he had some qualities; but whatever they were, they didn't include a Byzantine mother, a future Byzantine wife, or much in the way of Byzantine influence. Any attempt to form a true synthesis between Byzantium and the early Holy Roman Empire died with Otto III in an Italian marsh in 1002.