As far as I know, there had been a lot of tension ever since Rome conspired with the barbarian King Charlemagne to prop up the old corpse of the Western Roman Empire while the real official Roman Empire was still living on in Constantinople. Over the years, Rome became awfully power grabbing until the fall of Constantinople to the Ottoman Turks.

That's my opinion informed with what I digged up over the years regarding Eastern Rome/Constantinople. A lot of information about Constantinople have been intentionally fuzzied by the Vatican as well... so I'd say that look into it and see for yourself.