WARNING: The following contains spoilers for Episode 5 of Blade Runner: Black Lotus, "Pressure," airing on Adult Swim and now streaming on Crunchyroll.
Blade Runner: Black Lotus has primarily focused on Elle, a replicant with a mysterious past and highly advanced combat skills she's still learning about. In Episode 4, she learned she was originally supposed to be killed in a Doll Hunt, and she's now determined to seek justice for the murdered replicants. In Episode 5, she learns the identities of the other people who participated in the Doll Hunt, two of which are Earl Grant, the Chief of LAPD, and his wife.
Prior to Grant becoming aware of Elle having escaped her grim fate during the Doll Hunt, an LAPD officer named Alani Davis had been tailing her for the murder of Senator Bannister. When she presented Grant with her own evidence that Bannister's murderer was a replicant with a black lotus tattoo, Grant shut her out of the case. He even gaslighted her by telling her no replicant was involved in the murder as a way of protecting himself from incrimination.
With the knowledge that Elle is out there targeting everyone who participated in the Doll Hunt, Grant initiates a plan of his own to eliminate her. He does this by investigating her last known location and sends LAPD officers there to kill her. As a safety measure, he even calls a Blade Runner named Marlowe to retire her. However, Marlowe refuses his request the moment he hears LAPD are already on Elle's case.
Although Marlowe doesn’t have a prominent first appearance in Episode 5, he makes a huge first impression. In the first four minutes, he is seen stopping a bus in the middle of an LA street, seemingly to get on as a passenger. After briefly interacting with the other sole passenger on the bus, Marlowe identifies him as a replicant, which sends him running. However, Marlowe wounds the replicant before he makes it out of the bus and kills him in cold blood on the street. In just four minutes, Marlowe is established as a meticulous hunter of replicants with ruthless killing methods. This makes Marlowe an even deadlier Blade Runner than both Rick Deckard (Harrison Ford) and K (Ryan Gosling) from the Blade Runner films.
Originally adapted from Phillip K. Dick's famous novel Do Androids Dream of Electric Sheep?, Blade Runners (simply called bounty hunters in the original novel) are specialized officers who are contracted for the sole purpose of hunting down and retiring rogue replicants. Most Blade Runners like Deckard are assumed to be human, while others are confirmed to be replicants themselves. This is especially true of K from Blade Runner 2049, who is a Nexus-9 model.
Whether human or replicant, Blade Runners are not meant to empathize with their targets, and in that regard, both Deckard and K stand out. Deckard's ability to empathize and even fall in love with a replicant named Rachael seems to confirm he is human. K, on the other hand, shouldn't be able to empathize with his own kind, as he is specifically bioengineered to be a Blade Runner. Despite his replicant status, however, even K questions the status of replicants like himself when he discovers Rachael's remains and that she had produced a biological daughter with Deckard.
In contrast with both Deckard and K, Marlowe is shown to completely lack empathy for others, whether human or replicant. When interacting with other humans like Grant, he'll only acquiesce to his requests if he decides they're worth his time. He feels no obligation toward the Chief of LAPD whatsoever. When hunting down replicants, he shows no mercy for their plight and doesn't think twice about killing them cold. This could mean one of two things: he is either a human Blade Runner with a sociopathic personality, or he's an even deadlier replicant than Elle -- and possibly than other replicant Blade Runners.