|The Four Horsemen|
At some point during the Bronze Age (c. 3500 - 1500 B.C.) 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 be known as Death.
However, when Methos took the newly-immortal Cassandra as his slave and concubine after the Horsemen wiped out her tribe, he actually found himself beginning to care, though not well, and dissension appeared between him and Kronos, as Methos started to grow and Kronos did not. When Kronos demanded Methos "share" Cassandra as a spoil of war, Methos allowed it. He later witnessed Cassandra fleeing the camp after murdering Kronos, and did not stop her.
In flashbacks that are available in the DVD extras, approximately a thousand years later, in Ancient Greece, Methos had told Kronos that he wanted to be a scholar. Kronos asked what he had to learn, and Methos replied about who they were. Kronos was uninterested. "We are who we are, and that's more than enough." Methos replied it was not enough. Those who don't learn from their mistakes, repeat them. He slips poison into the wine he gives Kronos, a potion deadly enough to kill even him. Kronos would have taken Methos' head rather than let him leave the Horsemen. Methos imprisons Kronos underground, and it will be about a thousand years before he is able to escape, in the 7th Century A.D.
In 1997, Methos accompanied Duncan to a TV studio where Methos cheerfully tried out as a trivia game show contestant much to Duncan's disbelief and amusement. As the two men left the studio they both sensed another immortal. Methos asked if Duncan was expecting anyone, when Duncan said no, Methos decided to take the scenic way back and left MacLeod behind to see who the newcomer was after grousing that Duncan would live longer if he learned some caution.
Later, Methos was alone and heading 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.
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 from Duncan's loft and immediately challenged him. Methos insisted 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 Duncan 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 held her prisoner. She stormed out leaving Duncan behind stunned by the revelation.
True to form, Methos was next seen 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 replied, "The times were different, MacLeod. I was different. The whole bloody world was different, okay?" But MacLeod demanded an answer, frustrated, Methos complied: "Yes. Is that what you want to hear? Killing was all I knew. Is that what you want to hear?" MacLeod was ready to turn his back on his friend for that much of an admission, so the angry Methos elaborated, making the darkness of his past very clear.
"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.....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 walked away, angry and appalled. Methos was visibly upset and angry as well. The friendship appeared to be over.
MacLeod discovered Kronos' location though Cassandra's watcher who reported to Joe her leaving to confront Kronos. 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 in a river.
When Methos returned, he found MacLeod and Kronos fighting. Methos set the station on fire with strategically placed Molotov cocktails until the duelists were forced to stop fighting and part ways. That night, Methos met Kronos again and, and in order to prevent 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 spared Methos' life.
Methos and Kronos traveled to Europe and found Silas in a Ukrainian forest where he had lived alone 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 subdue the world.
Methos called MacLeod, for whom he had left a clue at the Romanian asylum, and arranged a meeting on holy ground. MacLeod met him after feeding Cassandra a lie. At the church Duncan asked Methos why he never told him about his past "Why do you think I didn't tell you? I knew how you'd react. What I've done, you can't forgive. That's not in your nature. Will you accept it?" Methos told MacLeod more of his history, including Cassandra's part in his past. He told MacLeod that he had to get Cassandra away, or she would die, 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 MacLeod where the bomb was and how to disarm it, but refused to go with him. Crossing Kronos openly was not yet on his agenda. MacLeod 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.
Caspian died on the Highlander's blade.
Duncan arrived at the submarine base to confront the surviving Horsemen. Kronos sent Methos to tell Silas to take Cassandra's head. With Methos seemingly abandoning him, MacLeod fought his best fight. Meanwhile, as Silas was about to behead Cassandra, Methos drew his sword, blocking his blade, Silas: "How can you do this? How can you go against what you are?" Methos: "You don't know anything about me!" Methos fought Silas, while MacLeod fought Kronos. 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. "I killed Silas! I liked Silas!"
All of Kronos' research and his exotic virus were destroyed, he was, in the end, not the end of time, merely history.