Jared Hopworth is a Boneturner, a skill that he has learned from The Boneturner's Tale, a Leitner tome. This book is likely linked to the entity known as The Flesh, due to Jared's abilities to manipulate bones and the statements he appears in which concern bodies, meat and being consumed by something - whether this is a literal consumption as in MAG 49, or a consuming desire for a perfect body, as in MAG 90.
Jared was a childhood friend of Sebastian Adekoya. When Sebastian left town to attend university they grew distant, and when Sebastian returned Jared started a campaign of petty terror against him. In September of 1996 at the Cheswick Library, Jared obtained The Boneturner's Tale (MAG 17).
It is likely that Jared used the Boneturner's Tale to learn the skill or power of boneturning: the ability to remove bones from living people without breaking the skin. It is likely that he practiced on his pet mouse and mother, who quickly returned The Boneturner's Tale to Cheswick Library. Jared returned to the library larger and bulkier than he had previously and likely full of other people's bones. He took The Boneturner's Tale from Sebastian and fled. It is possible that he was also responsible for Sebastian's later death.
Some 11 years later Jared had some connection with the Ukrainian mafia. He continued to boneturn in a butcher's shop in Stackwell, taking around 14 victims there to remove their bones and twist them into different shapes. Most of these bones he threw into a glistening, toothed hole in the floor. Eventually, when his last victim, Hector Lerado, died, he butchered his corpse and threw it into the hole as well (MAG 49).
It is clear that he is able to add bones to his own body, leading to the distorted figure that he now is. He is encountered by Ross Davenport as a gym owner in 2012. Their gym encourages people to push their bodies far beyond their normal limits, including illegal steroid use. Ross encounters creatures in the gym with impossible anatomies - including far too many arms - but is let go by Jared saying that it is "too soon" for Ross to join them (MAG 90).