The Proconsuls of Eurasia are the Eurasian equivalent to the nobility found in most other nations with monarchical practices. Proconsuls serve as active, voting members of the Senate of Eurasia, and are always members of Patrician families.
Within Eurasia, the concept of nobility is intrinsically and inseparably tied to the idea of the Senate itself, and as such one cannot be considered a "noble" if one is not a Senator. Indeed, most external scholars consider the Eurasian Senate to be sort of hybrid between a "Common House" and "Lords' House" of the legislature. A proconsul is an unelected member of the Senate, serving for life, who hereditarily receives their position based upon their family's status as a patrician household.
Proconsuls are not naturally given their seats, however. A proconsul must be elected by the Senate to fill his or her position. Almost always, with very few exceptions, the position is filled by a hereditary heir.