There was bo bloodline though. Until quite late (much to its detriment) the empire maintained some of its original “republican” character and the emperors derived their legitimacy from the will of God and the people rather than inherited it (which resulted in endless civil wars). Unlike in Europe in the medieval and the succeeding periods your bloodline/dynasty was secondary to your ability to take and hold power effectively making emperors closer to modern dictators than kings in some ways.
This is one of many ways the Russian claim to be the "Third Rome" is and was bullshit. The Eastern Roman Empire ended in 1453 with the fall of Constantinople, and it was the last polity with a credible claim to the continuation of the Roman Empire of old.
There was bo bloodline though. Until quite late (much to its detriment) the empire maintained some of its original “republican” character and the emperors derived their legitimacy from the will of God and the people rather than inherited it (which resulted in endless civil wars). Unlike in Europe in the medieval and the succeeding periods your bloodline/dynasty was secondary to your ability to take and hold power effectively making emperors closer to modern dictators than kings in some ways.