A Handlinger is a parasitic creature that resembles a purple hand, with the wrist area terminating in a long tail. Handlingers attach themselves to victims with their spiked tails, instantly killing the victim and allowing the handlinger to absorb their memories and personality.
Handlingers have two castes: The sinistral, or left-handed caste, and the dexterior, or right-handed cast. The left-hand "sinistral" noble class rule whichever secret handlinger community they are a part of, as they have the ability to shut down the dextrier's control over its host at will. These right-hand "dextrier" warriors, however, are perhaps more terrifying for a non-handlinger, as they are able to fly and spit fire using the body of whichever host they choose. Handlingers hide in plain sight, hidden under excessive fabrics worn by their hosts.
In the novels
Events of Perdido Street Station
Prior to and during the events of Perdido Street Station, handlingers are believed by many to no longer exist, and are often used to explain the strange behavior of others. However, the city boasts a small, secretive community of handlingers whose presence is allowed by the government.
11 years prior to the story, in 1768, New Crobuzon mayor Rudgutter turned his second-in-command, Montjohn Rescue, into a handlinger-host after Montjohn threatened to betray him. During the slake moth crisis, Rudgutter employs the service of ten handlingers (5 dextriers and 5 sinistrals) in an ultimately futile attack against the slake moths.
Events of Iron Council
Between the events of The Scar and Iron Council, the handlingers have agreed to have their presence in the city made public knowledge, along with the assertion that only the criminal condemned would be used as hosts. Due to internal politics handlingers were found on both sides of the Collective's failed revolution.