Grinders are people who practice extreme body modification - the term comes from computer gaming, where it refers to unlocking features (or, more commonly, improving one's character) through repetitive gameplay.
Grinders in Heavenside are seen as a lower tier of society and ignored. The appearance of Doktor Sleepless, coupled with him reviving Jamie seemly from the dead, have given them someone to rally around and a direction in which to vent their anger/frustration at a society as a whole that shunned and ostracized them.
In Issue11, Sarah Berlin tells Nicole that "...in New York [and] pretty much everywhere else..." the Grinders are viewed as Doktor Sleepless' "private army." The rub, as related to Sarah by Nicole, is that Sleepless doesn't really give them instructions: he merely provides them with tools and broadcasts his cryptic radio shows--stepping back from actual leadership and simply allowing the Grinders to do what they think he might want.
The fabricator dropped off at Shank Valentine (perhaps by Doktor Sleepless) is preprogrammed to create masks resembling Sleepless' face. The mask negates all RFID tags, allowing them to be anonymous to RFID-based surveillance equipment in addition to people and cameras.
They decided to use the face masks to go into central Heavenside and fuck up POD, because that is what they believe Doktor Sleepless has told them to do, through his broadcast. The fabricated masks provide the ability to do this with less of a risk of being identified.
Given Ellis' discussion of the power of one person having undue influence in at least one interview regarding Doktor Sleepless, it is perhaps relevant that John Grinder is the co-creator of neuro-linguistic programming. This is a subject that Ellis has also talked about in regards to his series Fell.
The Grinder symbol represents a gear-system that cannot function. The top gear would cause the two gears abreast of each other to grind to a halt at any attempt to rotate.
Appearances of the Symbol:
- Doktor Sleepless has a large grinder symbol tattooed on his back.
- The Doktor also projects a Grinder symbol in the air, similar to the Bat-signal from his house at Skartop Mountain.
- The Grinder symbol appears as graffiti on the Shank Valentine club in #001, and as street graffiti in #002, #007.
- On boxes distributed by the Doktor. (#007)
- The Mind Reader was wearing a Tshirt with the grinder symbol on it, black against a red background.
- On the cover to issue #4, a man is wearing a tank top or a t-shirt with the sleeves cut out, with the grinder symbol on it, black against a light blue background. The color is almost the same as the Doktor that is shown on the wall behind him.