Sung Guo

Sung Guo, also called Seneca Gracchus is an ancestor of Frank Zhang. Like all descendants of Periclymenus he was able to shape-shift.

History
He fought twelve Roman dragons and sixteen Chinese dragons in the western deserts of China.

The Son of Neptune
He didn't appear, but was mentioned by Emily Zhang in the rainbow image, Iris had made. Emily said he had been able to beet the dragons because he had been the strongest dragon of all.