Hiram is an antagonist in the Dan Vs. episode "Technology".
When Chris and Dan met him, he intended to eat them until he discovers Dan hates technology, upon which he takes them in. Though Dan and Hiram are initially friendly, Hiram grows violent when he discovers Dan likes television.
Hiram makes Dan and Chris sit through a puppet show detailing the awful things he'll do to them before trying to attack them with an axe. During the fight, Dan sets Hiram's shack on fire and the two friends flee, though Hiram begins to chase them without their knowledge.
At Barry Ditmer's company Omicron, Hiram arrives and manages to destroy Elise's controlling body armor with an improved version of the trick he'd taught Dan. Hiram then reveals that he used to be Ditmer's partner until Ditmer betrayed him and took credit for his inventions, after which Hiram decided to shun technology and go off the grid.
An enraged Hiram swears revenge on Ditmer after he takes revenge on Dan. Seeing this as an opportunity, Dan tricks Hiram into destroying Ditmer's main computer with his axe, causing the building to begin imploding.