Karseius II. was the son of Karseius I. The Elder who was the first Serpentlord of Near Harad. After his father's misterious demise he grew up in the Zarak region due the unstable situation his father left with his death in Near Harad.
As he came of age he returned to Near Harad where he took the throne of the Old Empire.
Karseius II. is concidered the most impactful Serpentlord of the Old Empire. His first half of his reign was dominated by success. He expanded Old Ain al-Harad to the biggest city on the continent and made shaped the Old Empire to become the most important power in the region, even surpassing Gondor.
This changed during the second half of his reign, after Near Harad lost the First Southern War with Gondor and it's allies. After this the empire suffered internal conflicts which resulted in the First Near Harad Civil War.
During the Principalities Karseius II. domintated the region from Ain al-Harad to keep the already confliting city states together. His death during the mysterious Doom of Old Ain al-Harad left Near Harad in a state of civil war which would later give rise to the New Empire.
Therefore Karseius II. memory is often disputed. While some people think of him as one of the greatest rulers in Near Haradrim History, others concider him responsible for the demise of the Old Empire as well as the break up of the Principalities of Near Harad.