Deldro Brody is a member of the secret society Libra, though he and his partner are unique in that they are two individuals inhabiting a single body. Deldro was originally a tall, slim, gray demon-like creature and a notorious serial killer with a cold-blooded and ruthless reputation. His personality is famously pessimistic and crude, standing in stark contrast to his physical partner.

Deldro's current state is the result of a forced transformation by Aligura, the Queen of Monomania. Aligura was in love with Deldro for his personality but found his appearance lacking. When she encountered the handsome and charismatic Dog Hummer, she devised a plan to combine the two into her ideal partner. She physically crushed Deldro into a liquid state, then completely replaced Dog Hummer's blood with this liquified form of Deldro. As a result, Deldro now exists as the very blood flowing through Dog Hummer's veins, and the two are now inseparable partners. After this transformation, Libra intervened and made the decision to seal both Dog and Deldro away in the deepest part of Hellsalem's Lot's largest prison due to Deldro's violent past and volatile personality, though they are sometimes released to aid Libra in dire situations.

In terms of personality, Deldro is the exact opposite of the ecstatic and overly optimistic Dog Hummer. He is generally pessimistic and crude, but since becoming Dog's blood, he appears to have mellowed slightly from his purely ruthless origins. He has shown genuine concern for Dog's safety, particularly when Dog's reckless behavior might endanger his physical body when they transform. Despite their contrasting natures, the two do not clash as much as one might expect; rather, they balance each other, with Deldro's pessimism keeping Dog's optimism in check and helping them think through problems together.

Deldro's primary function within the partnership is to provide immense physical power. His signature ability is to materialize from within Dog Hummer's body to form a gigantic, red and black demonic exoskeleton known as Exocrimson, which completely surrounds Dog and grants superhuman strength and durability. In this form, Dog can choose to poke his head out of the armor to communicate more personally, though this is shown to be dangerous. As Brody&Hummer, Deldro can perform several powerful attacks, such as forming his hand into a giant, hardened crimson fist for a devastating punch. He can also gather all of his blood into one massive fist, a technique that leaves Dog's body vulnerable but is capable of destroying enormous targets like Aligura's monster truck. Together, Dog and Deldro serve as a formidable, if volatile, asset for Libra, called upon when their unique, combined strength is required to face a crisis that ordinary methods cannot resolve.