The Blood Aristocracy makes a clear distinction between Blood Progenitors and Biological Parents. That distinction is encoded in the blood, an instinct that never needs to be taught. But in the case that the biological parent and Blood Progenitor are the same, the result is often impeccable. For high genetic compatibility is the only way to ensure a smooth Blood Conversion.
A fine example is Hakim, who as Shapur's grandson and only surviving relative, possesses the most compatibility with his grandfather's blood. But that compatibility still can't compare to Mithras, who is not only Odoacer's biological son, but a dragon lord from his mother's side.
AKA, while still an Imperfect Hybrid, Mithras' bloodline is already the strongest of the Spiritual World, unmatched and unparalleled. Add to that the Lord's tears, and the power of that blood…transcends even the divine.