You are referring to the Tsaesci, which is a race of vampiric snake-like people on the continent of Akavir. There are also 3 other races on Akavir, the Kamal, Tang Mo and Ka Po'Tun, but the influence you mention is from the Tsaesci. Several Tsaesci served in place of the Emperor, but that ended in the 2nd Era when the last one and his heirs where all assassinated.
The Emperor line is descended from Akatosh, who's avatar is a dragon and is stated to be the first of the gods. It is rumored that his blood was mystically joined with the descendants of Alessia, who was the first Empress. The Emperors weren't descended from the Tsaesci.
