Sebastian was a dreaded Kheran warlord who acted as the fearsome leader of the Knights of Khera, an ancient and legendary military Kheran faction who once acted as flagship of the Kheran fleet. Throughout their military history led by Sebastian, the Knights demolished the Fu'Ama Armada, leveled the Goladean Fortress Moons, razing the Regenerator Armies of the Samilat Hierarchy. Among the crew of the Red Blade many of them are warlords who trained under their leader Sebastian himself, with even Majestic served him and the Knights for a time. 
Ten millennia ago, the Sebastian and his Knights helped fend off an invasion from the Bleed, but even with their help the Kherans were losing. Sebastian and his knights drove the enemy into The Bleed long enough for the rift to be sealed with them aside, presumably dying. 
After the World's End, the Sebastian and his Knights returned when the generator powering the Masking Wall in Finland snagged on a quantum tether which tore open a rift into The Bleed. They then used this as a staging ground for their plans to terraform Earth by wiping out its existing inhabitants so they can claim the planet as "New Khera". The Knights were discovered by The High and eventually came into conflict with StormWatch when they tried to destroy their orbital base before being stopped by Fuji.  Sebastian and his Knights tried to directly destroy the Stormwatch base, but tricked into ramming into the station, damaging his ship and leaving an injured Sebastian floating in orbit. 
The Knights later attempted to intercept the Authority's departing Carrier in UnLondon and openly waged war against Earth's gathered heroes. The fighting was temporarily interrupted by another invasion from Sliding Albion led by Prince Yngvi. Sebastian quickly decapitated its leader and Knights successfully devastated that invasion before resuming their battle against Earth's forces.
During an all-out battle on the UnLondon ruins, the Knights had to separately defended their terraforming devices when Spartan of the Wildcats ordered Fuji in teleporting some of Earth's heroes to destroy the devices at Earth's magnetic poles. Sebastian and his small group of Knights continued their battle in UnLondon, while other Knights were sent to the poles to guard the terraforming devices. Eventually, the core members of the Knights were killed leaving an enraged Sebastian to combat the Earth’s heroes and cripple Majestic. The terraforming machines were teleported into the Red Blade flagship by Redeemer, Disperse, Dingo, H.E.R.B. and Geek. A angered Sebastian stormed into the Red Blade and killed those for destroying the ship. The Red Blade and Sebastian, and along with Redeemer, were banished again into The Bleed by Link, who opened several Shift-Doors to The Bleed and ending the threat of the Knights of Khera.
- Kherubim Warlord Physiology: As a Kherubim Warlord, he is a rare type of "Enhanced" Kherubim, with abilities far beyond those of the average member of his race. He is an exceptionally powerful Warlord even among members of his own kind and was capable of easily overpowering Mr. Majestic and leaving him catatonic. He was powerful enough to easily dispatch Omni and Apollo.
- Genius Level Intellect: Sebastian possesses such intelligence that it would be classified as superhuman.
- Hand-to-Hand Combat (Advanced)
- 7 Appearances of Sebaeos (Wildstorm Universe)
- 2 Images featuring Sebaeos (Wildstorm Universe)
- Quotations by or about Sebaeos (Wildstorm Universe)
- Character Gallery: Sebaeos (Wildstorm Universe)