Silas was an Immortal, also known as War of "The Four Horsemen," a group of Immortals who pillaged and killed during the Bronze Age. A brutal murderer, he also had an almost childlike quality when not engaged in the Horsemen business.
The burly Silas loved nothing more than to kill, to conquer, to be feared. The power of the Horsemen was his joy and reason for living. Although he did not get along with fellow Horseman, Caspian, he seemed to look up to the thinker, Methos.
After the Horsemen disbanded, after Methos disappeared, Silas eventually retreated from the world he no longer ruled. For centuries he lived in isolation in the forests of Ukraine. In 1997, he finally sensed the presence of another Immortal, Kronos and Methos had come for him at last.
The three Horsemen traveled to Romania to obtain the release of Caspian from an insane asylum. They regrouped at an abandoned submarine base in Bordeaux, France. Delighted to be among his 'brothers' again, Silas did not understand that their proposed destruction of the world must take a strange and unfamiliar route, biological weapons: "I don't like this killing from a distance. I like to feel my axe in my hands. Look into my enemy's eyes before I strike."
Silas is the only member of the Horsemen Methos actually liked, he feared Kronos, and hated Caspian, but there was something about Silas, and he tried to coax him over to sanity, telling him they didn't need what they had in the bronze age, they could live without it. Silas replied eagerly, "And for 2000 years, I've dreamed of the day when we would ride again! Like you always said, Methos - we live, we grow stronger, and we fight." Methos reluctantly realized there was no way to reform a mind set 3000 years in the past.
Kronos dispatched Silas and Caspian to deal with Duncan MacLeod, but in the ensuing fight, MacLeod beheaded Caspian and escaped Silas by throwing himself off a bridge. Silas reported Caspian's death and was sent to watch over the prisoner Cassandra, whom he was to behead the moment MacLeod appeared. When Methos stopped him from killing her, he became confused and angry, "How can you do this? How can you go against what you are?" While Methos who had changed so much was angry that Silas could not, or thought he knew anything about him after so long,"You don't know anything about me!" Furious at the perceived betrayal, Silas swung on his former brother and the two fought, even as MacLeod fought Kronos, their battle ranging throughout the base, as the agile Methos dodged the lumbering Silas' heavy axe and brute force attacks.
At last, Silas was beheaded by Methos at almost the same time that MacLeod beheaded Kronos. Duncan and Methos receive a Double Quickening. Having at last finshed something he had avoided for thousands of years, Methos was shattered after the death of Silas. "I killed Silas! I liked Silas!"
According to Highlander sword master F. Braun McAsh, the backhanded beheading stroke Methos used on Silas was a result of Bronze Age weapons being shorter and less sharp. The backhand that started over the head developed enough power to compensate for this.