|The Four Horsemen|
At some point during the Bronze Age (c. 3500 - 1500 B.C.E.) Caspian, Silas, Kronos, and Methos came together and formed a group of raiders that came to be known as the Four Horsemen (eventually of the Apocalypse). As the strategist, Methos organized many of their tactics, and came to think of himself as Death (Observation and Caspian's own words in The Pain Eater indicate that Caspian served as Famine while Silas and Kronos were likely War and Pestilence or Conquest respectively). However, when Methos took the newly-immortal witch Cassandra as his slave and concubine after the Horsemen wiped out her tribe, dissension began to surface between himself and Kronos. When Kronos demanded Methos "share" Cassandra as a spoil of war, Methos allowed it. He witnessed Cassandra fleeing the camp after murdering Kronos and did not stop her.
Dilijan, an ancient immortal partially responsible for the creation of the Four Horsemen, sent one of his acolytes to the Horsemen, a manipulated immortal (by this point Dilijan was able to manipulate Quickening energy and the knowledge associated with them to the point that he could manipulate his 'emptied' immortals into obedient tools) named Kyne. Kyne lured the Horsemen into a journey by boat and once the group was vulnerable he committed suicide. His Quickening ignited lamp oil stored in the ship's meager hold blowing it up and scattering the Horsemen.
In 1997 Methos accompanied Duncan to a TV studio where Methos cheerfully served as a trivia game show contestant much to Duncan's surprise and amusement. As the two men left the studio they both sensed another immortal. Methos asked if Duncan was expecting anyone, when Duncan replied no, Methos decided to take the scenic way back and left Macleod behind to see who the newcomer was after grousing - in his typical manner - that Duncan would live longer if he learned some caution.Later, Methos was coming out of the building he was staying in carrying a backpack to his car when he sensed another immortal. "MacLeod?" He turned, looking for his friend, only to take a knife to his chest. Kronos stepped up to him, smiling. "Kronos!" Methos choked in horror as he died. He woke up in an abandoned power station where Kronos offered him an ultimatum, join him or lose his head. Faced with a no-win situation, Methos chose to survive. But Kronos demanded a test of loyalty, since Methos could never bring himself to kill Cassandra, Kronos would do it for him, and, in return, Methos would kill MacLeod since he and Kronos had an ugly history of their own.
Methos arrived at Duncan's dojo, looking a flustered, but before he could explain the situation, Duncan asked him if he had ever heard of Kronos, Methos was taken aback, but before he could answer, Cassandra arrived in the freight elevator from Duncan's loft and immediately challenged him. Methos swore that she didn't know him and fled while Duncan ran interference with Cassandra. Cassandra was livid, especially as Duncan prevented her from following Methos. Once Dunacn was certain Methos was gone he released Cassandra and she told the Highlander that his friend had ridden with Kronos - he was one of The Four Horsemen - and it was Methos, not Kronos, who had captured her and held her prisoner. She stormed out leaving Duncan behind utterly stunned by the revelation.
Methos was packing his car presumably to run when he sensed Duncan. Duncan demanded to know if what Cassandra had said about Methos and Kronos were true. Methos tried to brush it off and convince Duncan to leave it alone until he realized that Duncan was never going to let it go. Methos then told him that it was true, he had ridden with Kronos, they killed thousands and they did it for pleasure. He asked Duncan if that was what he wanted to hear, because the answer was definitely yes."I killed. But I didn't just kill fifty, I didn't kill a hundred. I killed a thousand. I killed TEN thousand! And I was good at it. And it wasn't for vengeance, it wasn't for greed. It was because...I liked it. Cassandra was nothing. Her village was nothing. Do you know who I was? I was Death. Death on a horse. When mothers warned their children that the monster would get them, that monster was me. I was the nightmare that kept them awake at night. Is that what you want to hear?! The answer is yes. Oh, yes."
Macleod stared at him and told him that their friendship was over. He walked away, appalled at what Methos had told him. When Duncan departed Methos was visibly upset. After leaving Methos Duncan discovered Kronos' location as a result of Cassandra leaving to confront him. Cassandra challenged Kronos but was no match for him, she tried to run for her life but she ran into Methos who knocked her out and dumped her body into a river. When Methos returned from dumping Cassandra, he found Duncan and Kronos fighting. Methos set the station on fire with strategically placed Molotov cocktails until Duncan and Kronos were forced to stop fighting and part ways. That night, Methos met Kronos again and, in order to prevent a frustrated Kronos from killing him, Methos revealed that he knew where Silas and Caspian were. Kronos initially didn't believe him but finally agreed to seek them out and spare Methos' life.
Methos and Kronos traveled to Europe and found Silas in a Ukrainian forest where he had lived for centuries and Caspian in Romania where he was incarcerated in an insane asylum after being convicted of brutal cannibalistic murders (in The Pain Eater Caspian's incarceration is further explained). The Four Horsemen then left for Bordeaux, France and an abandoned submarine base, once there Kronos revealed that he had developed a biological weapon and intended to use it to take over the world.
Methos called Duncan for whom he had left a clue at the Romanian asylum and arranged a meeting on holy ground. Duncan met his former friend after feeding Cassandra a lie about a problem with his credit card at the front desk of their hotel. At the church Duncan asked Methos why he never told him about his past and Methos explained that hehad known how MacLeod would react. What Methos did was beyond MacLeod's ability to forgive. Methos told Duncan that he had to get Cassandra away from Kronos, as none of them could stop him then revealed Kronos' plan.Methos explained that Kronos didn't really want to rule the world, he wanted to watch the world burn. Kronos had been experimenting on monkeys to develop a virus worse than Ebola which he would use to blackmail the world's nations into submission. His first test would be that night - a bomb in a fountain. Methos told Duncan where the bomb was and how to disarm it, but refused to go with him. Crossing Kronos openly was not yet on his agenda. Duncan raced to the Place des Quinconces and arrived just in time to disarm the bomb. Kronos and the other two Horsemen in the meantime kidnapped Cassandra from the hotel. Upon realizing that Duncan had foiled his plan with the bomb in the fountain, Kronos sent Silas and Caspian to kill him. Duncan arrived at the submarine base to confront the surviving Horsemen after successfully killing Caspian and avoiding Silas. Kronos made Duncan an offer: if he laid down his sword, Cassandra would live, but if he fought, Cassandra would die immediately and Duncan would follow her. Duncan chose to fight, Kronos sent Methos to tell Silas to take Cassandra's head. With Methos seemingly abandoning him, Macleod fought his best fight. As Silas was about to behead Cassandra, Methos drew his sword. Silas thought Methos was challenging him for Cassandra's head, he stepped aside and encouraged Methos to kill Cassandra, instead Methos challenged Silas. Silas was shocked by Methos' betrayal and asked him why. Methos angrily told him "You don't know anything about me!" and struck Silas' axe beginning the fight. Methos and Duncan finally triumphed, they took their opponents heads at the same time and experienced a Double Quickening linking the two men together. In the aftermath, the only sound was Methos weeping. Followed by Cassandra's enraged scream as she came for Methos with Silas' axe. To her surprise and anger, Duncan insisted that she let Methos live.