Joshua Blay is one of the co-creators of The Ink Black Heart cartoon and ex-boyfriend of Edie Ledwell, the other co-creator. His representative is Katya Upcott, who also feels quite maternal towards him.

Josh is twenty-five during the events of the novel and is described as very handsome, with dark hair (which was long before being cut short in the hospital), large blue eyes, a finely drawn nose and mouth, a square jaw and high cheekbones. He’s a heavy drinker and smokes a lot of pot. Allan Yeoman says he’s charming, but doesn’t like confrontation or unpleasant conversations, and is a poor judgment of character. Josh doesn’t like being told what to do, but is more laid back than Edie. All he wants is an easy life. He doesn’t stick up for Edie when she is being abused online. Josh tells Strike and Robin that he talks too much and will tell anyone anything, which concerned Edie.

Josh was raised by a single father, who is a “raging alcoholic,” but they are no longer in touch. He grew up on the Lismore Circus estate, which is also where Wally Cardew lives with his grandmother and sister; Josh likely became friends with Wally on the estate. He attended St Martin’s art school, where he became friends with Seb Montgomery. Josh got chucked out of the school for “bein’ a slacker” but remained friends with Seb, who helped animate the first episode or two of the cartoon before they didn’t need him any more. While at St Martin’s, Josh dated Kea Niven, who later claims that Edie stole all her ideas for The Ink Black Heart cartoon.

In addition to Wally and Seb, Josh is also friends with Tim Ashcroft, Pez Pierce, Nils de Jong and Mariam.

Josh and Edie met whilst living at the North Grove Art Collective and came up with the idea for The Ink Black Heart cartoon in Highgate Cemetery one evening. Josh and Tim Ashcroft were stoned at the time.

Their first-ever interview was posted on YouTube in June 2010, after the first two episodes of the cartoon had been released. It was filmed by Tim Ashcroft in a bedroom in the North Grove Art Collective. In the interview, it is clear to Robin that Josh, aged twenty at the time, and Edie, twenty-five, were smitten with each other.

In January 2015, Drek’s Game user LordDrek persuades the person behind the username Hartella to pass over a dossier to Josh Blay with evidence that Anomie is in fact Edie Ledwell. Hartella was once Josh and Edie’s personal assistant. Josh confronts Edie over the phone about the rumour that she’s Anomie and they argue. Josh later confesses his regret that he believed Edie to be Anomie.

Edie tells Robin that Anomie appears to like Josh more than her, and seems to want Josh to take total control over the cartoon. Anomie helped fuel the online hashtag #IstandwithJosh. At one point, Josh believed that Anomie was Bram de Jong, the twelve-year-old son of Nils de Jong; Bram has an IQ of 140 and spied on Edie and Josh through a hole in the wall of the bedroom for weeks. Josh later dismisses the idea of Bram being Anomie.

On the evening of 12th February 2015, Josh meets Edie in Highgate Cemetery so he can show her the dossier of “proof” that she is Anomie. They are both attacked, leaving Edie dead and Josh in critical condition with stab wounds. He is taken to Whittington Hospital. Josh has situs inversus, meaning all his organs are reversed, in mirror image; Anomie thought he was stabbing Josh through the heart, but his heart is on his right side rather than on his left, so he punctured his lung instead. Josh was also wearing a thick jacket when he was stabbed, which helped stop the knife going any deeper, saving his life.

His assistant, Katya Upcott, visits him in hospital every day. She tells Strike over the phone that due to his wounds, Josh has Brown-Séquard Syndrome –- he is paralysed on one side and has lost all sensation on the other. He is later taken to the London Spinal Cord Injury Centre.

For a month before the attack, Josh was living back at North Grove Art Collective after his own flat on Millfield Lane was flooded. On visiting Lisburne Road to interview Katya, Strike and Robin learn from Inigo that Josh had previously turned up at their house drunk; Katya says it was “only a couple of times.” He stayed at their house the night before the attack, having being chucked out of the art collective by Mariam for supposedly falling asleep and dropping his spliff, setting fire to a wastepaper basket that also set fire to the curtains. Josh tells Strike and Robin that he believes it was Bram who set fire to his room.

While in hospital, Josh had Katya dictate a letter to be put in Edie’s coffin. On hearing that he’s done this, Edie’s boyfriend Philip Ormond does the same.

After recovering enough to talk, Josh tells Katya that his attacker spoke to him and said, “I’ll take care of things from here, don’t worry.” He believes that the voice was male, but not Bram de Jong, who he’d previously suspected.

In chapter 63, Strike and Robin interview Josh in the London Spinal Cord Injury Centre after he’s recovered enough to talk to them.