Final answer:
Darius eventually consolidated power in his own hands through his rise to the throne, quelling rebellions and strengthening his claim through marriages and royal lineage integration.
Step-by-step explanation:
In the given context, the entity that eventually consolidated power in his own hands is Darius. Darius was able to grasp control of the Persian Empire in 522 BCE and faced rebellions that he put down over a year. He further strengthened his claim to the throne through marriages and the integration of himself into the royal line.
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