BIOGRAPHY - Page 3
Caliban's troubles did not end there. A few days later, X-Force happened across Caliban inexplicably playing Chopin on the piano like a master musician, a talent he had never demonstrated in the past. Once he noticed their attention, Caliban lost his concentration and suddenly experienced a massive seizure that flattened him. After a second seizure nearly crippled him on a mission soon afterwards, Caliban was placed on bed rest until the source of his seizures could be ascertained. [X-Force (1st series) #65-67]
Unfortunately, this meant that the ailing Caliban was the only mutant in residence when Bastion and Operation: Zero Tolerance stormed the Xavier Institute and 
occupied the mansion. Fortunately, Cable in turn broke back into the mansion in order to prevent Bastion from getting his hands on Xavier's files and got Caliban to safety. That safety did not last long, however, as Caliban was approached by Apocalypse's servant, Ozymandias. It seemed that Caliban's current troubles were in part due to the genetic engineering Apocalypse used to shape him into a Horseman. Ozymandias had come to claim his master's former Hound. Using a psychic assault, Ozymandias brushed Cable aside and left him with the false memory that he had left Caliban in safe hands to discourage any possible pursuit as the vulnerable Caliban was brought back to Apocalypse. [Cable (1st series) #45-46, X-Force (1st series) #69-70]
In preparation for the gathering of the Twelve, Apocalypse put Caliban through another round of genetic enhancement and alteration. After gestating in a cocoon made of organic coral-like mass, Caliban emerged as Pestilence - the first of Apocalypse’s new Horsemen. His mind once again bent to the Eternal One's will, Caliban hunted down Cable and X-Force in San Francisco. 
Using the newly developed psychoactive virus Apocalypse had bestowed upon him, Caliban assaulted his former friends Warpath and Sunspot in both mind and body, prompting Cable to travel to the astral plane in an attempt to free them from the virus's effects. This was all part of Apocalypse's plan, however, as Cable's inert body was now vulnerable to capture by his servants. As a result, the first of the Twelve was taken prisoner. [Cable (1st series) #73-74]
Later, Caliban teleported to New York to attack Nate Grey in mid-air at Apocalypse's behest. Caliban knocked Grey unconscious and transported him back to Egypt, where Apocalypse planned to use the boy as his new host. Despite the X-Men's efforts, the rest of the Twelve were gathered and Apocalypse prepared to combine and absorb their powers to make his ascension. However, Apocalypse had miscalculated the then-weakened Magneto's power levels, which created a flaw in his mutant energy machine that allowed the Twelve to escape. Caliban and the other Horsemen attempted to block the fleeing mutants but Mikhail Rasputin leapt upon the Horsemen, using his residual dimension-hopping power to spirit them away from the field of battle. [X-Men (2nd series) #97]
Where Caliban ended up is unknown, but he was later seen in the sewers under Egypt, tracking down his former master. After the ceremony of the Twelve failed, Apocalypse had bonded himself to the body of Scott Summers, aka Cyclops. Once Caliban tracked down his master, "Apocalypse" hardly even recognized his servant. 
Whether it was due to Apocalypse's current status or dimension-hopping with Mikhail, Caliban began to shake off the brainwashing effect he had been subjected to before becoming a Horseman again. When Cable and Phoenix arrived in their search for Cyclops, Caliban recognized "Cable-Nathan" as a friend instead of an enemy, protecting him from the sniper fire of Gauntlet, another former servant of the Eternal One hunting them. During the chaos that ensued, Apocalypse re-manifested himself through Cyclops's body, and approached his former Horseman. For undisclosed reasons, Apocalypse chose to free Caliban from his servitude, producing an energy discharge that apparently cleared Caliban's mind of the influences that had been placed on him. [X-Men: Search for Cyclops #3]
After this, Caliban went into seclusion for a time, until he was kidnapped by the Watchtower and its malevolent Administrator. The Administrator had learned of the mutant-devouring scourge known as Skornn and planned to use Caliban's tracking abilities to hunt down the creatures for his own purposes. Luckily for Caliban, Wolverine and X-Force broke into the Watchtower and got Caliban to safety before he could be used as the Administrator's stalking horse. He rejoined X-Force briefly to end the threat of the Skornn, but went his own way again after the creature was defeated in Manhattan. [X-Force (2nd series) #4-6]
After the incident referred to as “M-Day,” when more than 90% of Earth's mutant population was depowered, many of the remaining mutants flocked to the Xavier Institute for sanctuary. Caliban and several of his fellow former Morlocks were among them. [X-Men: The 198 #2] The conditions were less than ideal, 
though - the U.S. government took an interest in the continued existence of the remaining mutants on Earth. Through their agency, the Office of National Emergency, they unilaterally declared the Institute a closed reservation, effectively keeping Caliban and the other mutants there prisoner "for their own protection." Even the X-Men could not leave the Institute unescorted by a Sentinel Squad O*N*E handler. Caliban soon grew tired of this imprisonment and sent word out to his former X-Force teammates, Domino and Shatterstar. They arranged a "jailbreak" and one night Caliban worked with the 198 to stage a riot inside the camp, drawing the Sentinel Squad's attention long enough for X-Force to slip in and blow up the outer wall. Caliban, X-Force and more than half the 198 made their escape aboard a shuttlecraft, heading for a new sanctuary. [Civil War: X-Men #1]
With the Superhuman Civil War raging in New York, Domino had made contact with Captain America's resistance and learned the location of an abandoned SHIELD base in the Nevada desert. 
The 198 set up camp there while they waited to plan their next move. In searching the sub-basements, Caliban found a large stockpile of weapons of mass destruction. Matters became critical when the Sentinel Squad and a set of superhuman operatives tracked the 198 to their new base. The O*N*E's crazed leader, General Lazer found the command codes to activate these forgotten weapons and locked the 198 inside with them after triggering them to detonate. Working together, the 198, the X-Men and the various government forces managed to break open the base's blast doors, freeing all the mutants in time to get a safe distance away before the detonation. Following this incident, the president modified O*N*E protocols, thus allowing the 198 to move about freely again. [Civil War: X-Men #2-4]
Caliban chose to return to the Morlock Tunnels with Leech and sought out the remnants of his people, those few who still remained mutants and those who had lost their powers to the Decimation. In the Alley, they were assaulted by Masque and a small cult of former Morlocks, who were driven to follow the prophecies of one of their own who had foreseen M-Day and its consequences. Masque cruelly turned his flesh-shifting ability on Caliban, destroying a good portion of his muscle mass and leaving him emaciated and weak. In his depleted state, Caliban barely
managed to make his way back to the Xavier Institute, where he was found by his old teammate, Warpath. The X-Men nursed him back to health and Caliban joined them in hunting down Masque's group of "eXtremists" before they could do too much damage. They found Masque attempting to detonate a crowded cathedral on a Sunday morning, in hopes that the loss of human life would show that mutantkind still posed a legitimate threat to baseline humans. The X-Men broke free from Masque's trap, though, and Caliban personally beat him into submission. [Uncanny X-Men (1st series) #487-491]