He first met Slade in the army shortly after he became a mercenary and saved Joseph on a mission. Since then, he became Slade's weapons designer. Shortly after giving the Ikon suit to Slade, Slade discovered David's relationship with Joseph. He felt betrayed that one of his closest friends and a man that Joseph had known as an uncle was dating him and Slade attacked David and beat him badly. He was hospitalized and supposedly died. It was revealed that prior to his death, he had been experimented on by Dr. Villain using Slade's blood in an attempt to make a new super formula to save him, which seemingly didnt work. However, the serum was activated after death and turned him into a brutish monster. Wanting revenge on Slade, he wore Deathstroke's old costume and hunted him down. He then revealed that it wasn't Slade who had killed him, as he had survived the fight, but Joseph who had pushed David off the building, feeling insecure. He also told Slade that it was really Adeline who had manipulated Slade into wearing the Ikon Suit.
After this encounter, Slade started going crazy and hallucinating Wintergreen so David returned again to help Defiance take him down and send him to Arkham Asylum. Shortly after this, an alternate reality counterpart of Slade arrived and threatened Slade's family. At the same time, Jericho received an upgrade from Lex Luthor that made him far more powerful at the cost of his own sanity. Slade asked David a favor in order to stop both problems. First, David helped Slade beat the alternate version of him. Then David confronted Jericho. They both went to space to talk and David used his technology to lock onto the energy signature to lock onto the diode powering Joseph and pull it out. He created an energy bubble around Jericho while the diode latched on to him, creating an explosion that killed David as his final sacrifice to save Joseph.
- Virus Infection: To save David's life, who was almost killed by Jericho, Dr. Villain infected him with a virus synthesized from Deathstroke and Jericho's DNA. His body's immunity system mutated to combat that virus, granting him super-powers. (see Weaknesses below for bad side effects)
- Genius Level Intellect
- Virus Infection
- Missing Eye: He had his left eye removed.
- He is Catholic.
- It was he who gave the alias Jericho to Joseph based on the Bible. It was about justice breaking down strongholds.
- 17 Appearances of David Isherwood (Prime Earth)
- 7 Images featuring David Isherwood (Prime Earth)
- 2 Quotations by or about David Isherwood (Prime Earth)
- Character Gallery: David Isherwood (Prime Earth)