Aden Searlin was the second Pendragon of Slayer Dragons, and the last Slayer Dragon anointed by Eieber. Aden was not one of The Ten and was not alive during the Mage Wars, being only 41 at the time he was made Pendragon.
Aden came to power at a tumultous time. Eieber's death had essentially ended the Old Alliance, and two previous attempts at uniting the various powers had already failed (the Ruling Council and the Ministry of Earth).
For Aden, it was a dangerous and difficult time to take up the sword. He had essentially inherited a huge problem, and the other Slayer Dragons were mostly too old to help. In his first year alone, Aden anointed three new Slayer Dragons of his own. His successor was Jayce Spearlock.
Aden Searlin is perhaps best remembered for the Earth Sphere Unified Nations, a system which failed to unite the crumbling Alliance, but ultimately provided stability and prevented war for the next 700 years.
Were it not for Aden, the Mage Wars may very well have resumed upon Eieber's death, and the Golden Age of the Slayer Dragons might never have come to pass. This is all the more poignant, when it is remembered that Aden might have been a descendant of Nathan Searlin, who started the Wars.