Brett Hull works for Pawnee Animal Control along with Harris. Leslie describes them as "burnt-out morons". Pawnee: The Greatest Town in America states that Harris and Brett took over as Co-Directors after longtime director Eugene Dredge retired last year, presumably to spend more time smoking marijuana.
In "The Possum", Leslie Knope is asked to assemble a task force to catch Fairway Frank, a possum accused of biting Mayor Gunderson's dog. When she asks for the two best guys to join her and be part of her task force, Eugene tells her that would be Brett and Harris. Brett is confused as to how the Parks and Recreation Department employees know his name, even though he's wearing a nametag.
In "April and Andy's Fancy Party", Brett and Harris are present at Andy Dwyer and April Ludgate's wedding. They attempt to release doves after April and Andy say their "I Do's", but the one that Harris throws into the air falls to the ground, dead.
In "Animal Control", Chris Traeger steps on a coyote trap during a visit to the Animal Control Department and subsequently fires both Brett and Harris. Later in that episode Brett attempts to reapply for the position while high but is scared off when April asks why there are so many police outside city hall. In "Are You Better Off?", Brett and Harris are seen in formal attire presumably voicing their displeasure with Leslie as Councilperson.
Brett lists his love of burgers as a qualification during his reapplication for a position in Animal Control.