In a police department filled with corruption, Harvey Bullock is one of the few cops to swear complete allegiance to Jim Gordon.
Batman has his many Robins, and Commissioner Gordon has Detective Harvey Bullock.
Sure, he’s a bit rough around the edges (you wouldn’t want to take him to a party), and he’s not particularly fond of Batman, but he’s a crack shot, loyal to a fault, and he knows the streets of Gotham like the back of his hand.
A hard-boiled GCPD cop, Bullock is the definition of grizzled, but don’t let that make you think he isn’t committed to his work.