Prior to being broken out of the mental asylum in Romania Caspian was drugged and presented with an outside expert ostensibly testing a new technique to engage disturbed patient's layers of personality to gain access to the core personality.
The expert, Elena, asked the core Caspian personality about his past. Caspian didn't remember the past few thousand years passing, his last memories were of an ancient battle and its aftermath. His people were hunter gatherers, they used wood, stone, and bronze tools. He was trampled to death by Karniel's invading army. After recovering from his death - not fully realizing he had actually died - he hurried to his camp only to find everything dead and burned. He found his father's corpse near a river and pulled a sword from it, it was a bronze blade nicked and battered by contact with bone and other swords, his first ever sight of a weapon designed solely and only to kill other people.
Caspian described Karniel as having difficulty speaking suggesting that he was so old language was a recently learned skill. He described the difficulties Karniel must have faced when he forged his army, the immortals he would have had to kill to keep order, and noted that no one else has ever managed to reproduce the feat.
Caspian and a small core group of immortals recruited mortal warriors to their side and engaged Karniel's immortal army. During the battle, known as Kamtal, Caspian faced Karniel alone and with the coordinated assistance of the mortal warriors he managed to triumph and kill Karniel. Sadly the Quickening drove him utterly mad and took him over, Karniel was so old and strong that his Quickening maintained his personality after being absorbed by Caspian. Caspian lashed out at his allies and enemies alike until he was driven from the field and abandoned the fight.
Shortly after the battle Caspian encountered the Dilijan, who would become the Pain Eater, for the first time. Caspian begged for help, Dilijan obliged applying a primitive and agonizing trepanning contraption to Caspian's skull. However, instead of helping Caspian control Karniel, the procedure weakened Caspian and strengthened Karniel. He wouldn't recall the procedure until he encountered the Pain Eater again centuries later.Upon their second meeting Dilijan explained that Caspian was most likely impacted by a Dark Quickening, he explained that Caspian had two options, he could seek out and kill righteous immortals to attempt to counteract the Dark Quickening but it would take centuries and require dozens if not hundreds of deaths or he could allow the Pain Eater to attempt to heal him.
They were trapped in a room with one of the Pain Eater's acolytes. Dilijan explained that should the procedure fail, or Caspian kill him or Piotch after losing control, the other acolytes outside the room would seal Caspian in. He then explained that he was going to use a copper tool inserted into Caspian's brain to heal him. Caspian recognized the tool and attempted to resist Dilijan. As he was restrained, the Pain Eater revealed that he had 'healed' Caspian before.
Once Caspian recovered from the second procedure, Dilijan explained that the last procedure failed because of the equipment he had been using. Caspian seemed calmer and more himself though the Pain Eater pointed out that the evil energy of Karniel was shunted from Caspian to the acolyte Piotch, turning the man into a raving wreck. Caspian admitted that he felt better but not like his old self. Dilijan pointed out that the new Caspian was an amalgam of his original self and all the righteous immortals Caspian had slaughtered while under Karniel's power. He then confessed that he had inadvertently drained Caspian's positive qualities instead of the darkness of Karniel during the first procedure, worsening Caspian's condition.
Caspian forgave Dilijan and said he was looking forward to a life of redress for the wrongs he had committed now that he was calm and sane again. Two months later, Dilijan asked how Caspian had progressed. Caspian praised Dilijan's work and his acolytes, and expressed gratitude for his assistance, support, and training.
Dilijan encouraged Caspian's progress then told him that he had more to learn and a new arrival to the compound, a grieving woman named Ashka, would be the instrument of his last lesson. The Pain Eater noted that her treatment would be simpler and more straightforward than Caspian's since she was not possessed. Later, he brought Caspian to view Ashka, Caspian observed her condition: she lay on the trepanation frame utterly catatonic in her despair, head shaved, wearing yellow robes. Dilijan was disappointed that Caspian could not see the beauty in her surrender to her despair, then proceeded with her treatment.
Caspian expressed concern when Dilijan did not kill Ashka prior to the 'treatment' to spare her the pain of the procedure. Dilijan revealed that he would absorb her despair himself, noting that he was known as the Pain Eater for a reason, he then performed the treatment and utterly drained Ashka's Quickening taking her memories and personality along with her pain.
Caspian was distressed and disturbed by the treatment. The Pain Eater admitted he had fought at Kamtal with Caspian, although Caspian never saw him. The Pain Eater led Caspian's pursuers away from him after the battle and doubled back to kill Caspian. Instead of successfully killing Caspian he performed the first procedure, but botched it and absorbed Caspian's virtues - virtues that had guided Caspian to help create the mortal/immortal army and face Karniel alone, risking sanity to stop the monster - the Pain Eater was inspired to create his order and recruit his acolytes to assist in healing immortals and mortals alike. He did admit that he made errors along the way and alluded to the ruining of Silas.
He then described Kronos' betrayal of him and said he abandoned his dream of a brotherhood bringing positive change to the world and focused on creating a new community that thrived happily for fifty years until Kronos and the Horsemen arrived and slaughtered his people, but spared Dilijan and swore to find him every fifty years and wipe out whatever community he had created.
He had fled and hid licking his wounds before he eventually decided to create his new order and become the Pain Eater. He says that eating the despair of immortals is his penance for creating and empowering Kronos, Silas, Methos and Caspian. Caspian reacted angrily as he realized that the Pain Eater had always known he was one of the Horsemen since he arrived at the sanctuary, and he was not just the Pain Eater but also Dilijan, the man Kronos hunted.
Dilijan revealed that he broke up the Horsemen and healed Caspian's sanity just so he could take it away again in revenge for the actions of the Horsemen and the slaughter of his people. Caspian attempted to resist but collapsed as he had been drugged or poisoned by Dilijan. He came to in the trepanation room where Dilijan had prepared his unconscious body for a reverse procedure.
Caspian begged Dilijan to leave him be and allow him to make restitution and amends, pointing out that Karniel was the source of his evil actions and Karniel was gone. Dilijan, long corrupted, told him he was determined to punish Caspian anyway, hellbent on vengeance he wouldn't settle until Caspian's name was synonymous with terror and blood and all memory of his sacrifice at Kamtal was utterly forgotten. In despair Caspian begged Dilijan to simply kill him outright; he can't stand becoming a monster again. Dilijan refused and laughed at Caspian's despair, then admitted he had become addicted to despair and liked the taste of Caspian's in particular. Dilijan said that this time he was going to remove all of the goodness he had left behind as well as returning Karniel and Caspian's own despair, effectively resetting Caspian's progress to redemption. As Dilijan began the procedure he promised to allow Caspian one thousand years to improve himself before he would repeat the procedure and hollow him out again.
As Caspian finished his story, Elena went over the high points in disbelief, then asked him why he chose to be Famine among the Horsemen, Caspian said the others were already War, Death, and Pestilence so he took the best title left, Famine. He went on to say that he was not his insane self, but he could feel that self banging at the walls of his prison.
Elena then asked why he killed his most recent victims. She asked if the Pain Eater had brainwashed him into cannibalism. Caspian asks questions about the state of the corpses found in his home and whether the investigators found a room with an apparatus in it. She described his killing room and he laughed at her saying the body parts found were from immortals and he was using them in his experiments, attempting to duplicate Dilijan's work. Elena then admtted that she was there on behalf of Dilijan, Dilijan was concerned that Caspian was trying to duplicate his work so he had sent Elena to interview Caspian.
Caspian was amused and noted that the new 'treatment' she had given him must have contained a drug to dull his immortal senses, he lauged at her and called her Ashka. He challenged the veracity of her memories and threw her real identity back in her face then pointed out that Dilijan hollowed him out so there should be no sane core personality for her to speak with. He admitted he had been leading her on, telling her his story while working his bonds loose, he breaks free and attacks her mocking her nature and declaring she isn't even human, just a reminder from Dilijan. Cheerfully crazed and violent he wedges her against the door to keep the staff from interrupting, debates releasing her back to Dilijan, then kills her for the fun of it.