He is very hard of hearing (wearing large hearing aids) and thus speaks very loudly. He often misunderstands what is said to him and replies with comically inappropriate responses. Cole's coded messages sometimes baffle even his closest colleagues. In the first episode in which he appears, he says, “Cooper, you remind me today of a small Mexican chihuahua” (which he pronounces "chee-WOW-wow"). The conversation continues as normal, with the issue remaining unsolved.

While in Twin Peaks, Cooper and Cole go to the Double R Diner where he is smitten by waitress Shelly Johnson, whom he apparently can hear perfectly well. Shelly, being ignored by her boyfriend Bobby Briggs at the time, is shocked yet pleased by his attention, and upon his imminent departure they share a kiss, to the chagrin of Bobby, who happens to show up at that moment.

At the beginning of Fire Walk With Me, Cole briefs agents Chester Desmond and Sam Stanley on their assignment to investigate the murder of Teresa Banks. Cole uses a coded language, in the attire and gestures of Lil the Dancer, to inform the agents of what to expect in their investigation. Cole describes the Teresa Banks murder case as one of his “blue rose” cases. The 2017 series reveals that "blue rose" refers to the Blue Rose Task Force, which investigates cases, particularly those involving apparent doppelgängers, that cannot be explained by rational means. Cole and Phillip Jeffries investigated the first "blue rose" case, where a woman was killed by another woman who looked exactly like her, and uttered the phrase before her body disappeared.

By 2014, Cole has become the FBI Deputy Director, and obtains improved hearing aids, resulting in fewer instances of him misunderstanding others. When at their maximum volume, Cole is able to speak quietly and hold private conversations, although he only occasionally raises the volume of the hearing aids as loud noises hurt his ears. After Cooper's doppelgänger is arrested in South Dakota, Cole leads the investigation alongside Albert Rosenfield and Tamara Preston. The three agents later take part in another case in South Dakota when a headless corpse found in the area is found to have Garland Briggs's fingerprints.