This node contains spoilers from the F. Paul Wilson novels The Tomb, Conspiracies, and All the Rage. Read no further if you don't want major plot points revealed before you read the books.
In F. Paul Wilson's novels, the rakoshi (singlular: rakosh) are demon-like creatures from ancient India. Roughly humanoid, they stand about eight feet tall, with cobalt blue skin and malevolent yellow eyes. They are incredibly strong, fast, and agile, and are armed with viscious fangs and razor-sharp claws on each of their three-fingered hands. They are virtually immune to almost all forms of attack, and feel no pain whatsoever. Iron can weaken them, but only fire can destroy them.
According to legend, ancient Old Ones, who predateded the Vedic and pre-Vedic gods, sought to take over mankind's place on earth. To this end, they took some humans and stripped them of everything good and decent, making them "hate, lust, greed, and violence incarnate." Giving the rakoshi an insatiable appetitie for human flesh, the Old Ones set them forth on earth to take humanity's place. Fortunately, humans turned out to be smarter than the creatures, and learned to control them. Ancient priests finally imprisoned the last of the rakoshi in caves in northern Bengal, and built a temple to Kali above. For generations, they kept and controlled the rakoshi. The Keepers of the Rakoshi wore magical necklaces, forged from iron and set with a pair of yellow stones resembling the creatures eyes, which healed them, prolonged their lives, and rendered them invisible to the rakoshi.
In 1857, Captain Sir Albert Westphalen, a British officer stationed in Bharangpur, India, heard rumors of this Temple-in-the-Hills and the incredible wealth kept there. He came to believe them, seeing a way to replace the family fortune he had squandered, and led a squad of troops to take the temple under the pretext of routing a band of Indian rebels. While the troops were looting barrels full of gemstones from the caverns, the high priest summoned the rakoshi. A terrible battle ensued, leaving Westphalen apparently the sole survivor. Using the temple's own stores of oil, he managed to wipe out the rakoshi and burn the temple to the ground. He later returned to England and concocted a story about finding a tremendous cache of gems hidden in the walls of Westphalen Hall.
But Westphalen was not the sole survivor. Though he had lost an arm to Westphalen's sword, the twelve year old son of the high priest, Kusum Bahkti, managed to make it out of the inferno with his sister Kolabati and their parents' necklaces. Kusum swore that one day he would bring to pass the curse his mother had pronounced on the Westphalen line: that they would all die in blood and pain for the atrocity he had committed. And when he and Kolabati found hidden in the burned-out caverns a sole rakosh egg, he knew he had found a way to live up to that vow.
Over a century later, Kusum, now a fundamentalist Hindu leader in India, started his plans in motion. He hatched the female rakosh egg he had, but lacking a male, he was forced to use himself as breeding stock to get a new nest started. Though this was the worst of blasphemies, he believed the divine hand of Kali was guiding him, and he would be forgiven. He put together his new nest in the hold of a steel cargo ship, and got himself transferred to London as part of the Indian Embassy to begin his search for the Westphalens.
The rakoshi's first victim was Richard Westphalen, a British playboy who had married an American woman to protect his share of the family fortune from the high British taxes. Kusum then sailed his ship to New York City, where the rakoshi made short work of Nellie Patton and Grace Westphalen, Richard's elderly aunts. Then it was time for the last of the Westphalens, seven-year-old Vicky.
Unfortunately for Kusum, Vicky's mother, Gia DiLauro, had become involved with one Repairman Jack, and he doted on Vicky. When she was abducted by a rakosh and taken back to the ship, Jack became a sort of berserk avenging angel. He managed to sneak onboard and plant incendiary bombs all over the ship before rescuing Vicky just as Kusum was preparing to hand her over to be devoured by the rakoshi. One rakosh followed them off the ship, but turned and swam back out when the bombs went off, killing the entire nest. Once again it seemed the rakoshi had been destroyed.
Several months later, Jack learned the true origin of the rakoshi. They were created by an entity known as the Otherness, which has been trying to take control of our reality for millenia. From time to time it has gained a toehold, but was thought to have been banished once and for all by a champion of its Enemy during World War II. Unfortunately, it managed to burst back through in the late 1960s, spawning one who would serve to open the way fully for its return. It was the Otherness that manipulated events to have Kusum Bahkti bring the rakoshi to America so they would be present when the time came for its agent to open the way. It was quite angry when Jack destroyed the rakoshi, and sought through one Melanie Ehler to have revenge upon him by mechanically opening a portal to it's reality and dragging him through. It failed, and Jack was free to continue pursuing his "fix it" jobs.
One of Jack's next jobs brought him once again face to face with a rakosh. Hired by a biochemist to investigate the hold a Serbian gangster has over her boss, Jack comes to find that her employer is manufacturing and selling the new designer drug "Berzerk." The drug gives feelings of invincibility and makes the user able to shrug off what should be incapacitating levels of pain and injury. It also releases the dark core of rage existing in everyone, no matter how polished their civilized veneer. Berzerk has one other decidedly strange property: every ounce of a given batch all becomes inert at the exact time of the new moon. Stranger still, the molecular structure changes, both in the compound itself, and in all representations of it, be they on paper, in computers, or even in people's memories.
Over the course of his investigation, Jack discovers the drug is processed from a molecule found only in the sickly "Sharkman" exhibited by Ozymandius Prather's Oddity Emporium. The "Sharkman" turns out to be the last of the rakoshi, the scar-lipped one he had last seen swimming back out to the sinking ship. It only remained weakened until Oz Prather learned what it really was, and what it's natural diet consisted of. Once Oz fed it human flesh, it quickly regained its strength and escaped into the Jersey Pine Barrens. Jack tracked it down and fought it to a draw, but finally decided to leave it there rather than returning with more firepower to burn it out. Though he doubted there had ever been a real Jersey Devil, he knew there was one now.
Sources:
Wilson, F. Paul. All the Rage. Tom Doherty Associates. 2000.
----. Conspiracies. Tom Doherty Associates. 2000.
----. The Official Repairman Jack Web Site. <http://www.repairmanjack.com> (February 28, 2003)
----. The Tomb. Whispers Press. 1984.