Josephus "Joe" Aloisius Miller was a hardened, world-weary detective. His work in the Asteroid Belt has shown him the worst sides of humanity. His new job, tracking down a missing girl, will change his life or end it.
An orphan, born and raised on Ceres Station in the Asteroid Belt, Miller and his fellow orphan Sematimba grew up in a life of petty crime just to survive. As they became adults, Semi told him "do you want to be the ass or the boot?" They both became cops. Miller now works as a detective with Star Helix Security, an Earth corp with the security contract for Eros. Choosing to work for Star Helix meant working for Earth – the oppressors of Belters like himself – but at least it put him on the winning side.
Miller has witnessed a lifetime of the horrible things people will do to each other out of greed, anger, lust, and desperation. He stopped trying to stem the tide of man’s depravity years ago, and is resigned to surviving as best he can. Despite the lack of rainy or sunny days in Ceres' subterranean colony, Miller wears a hat in defiance of the anti-Earth sentiments expressed by many of his fellow Belters.
In Season 1, his appearances are primarily of him searching for the missing Julie Mao, following every lead possible, even after finding out that the ship she was on was destroyed and being told by his boss not to worry about the job anymore, he leaves much of his side work behind in order to try and find out what happened to her. He meets the crew of the Rocinante on Eros and finds Julie at the end of the season, but she appears to have been killed by the Protomolecule infection.
As a member of Star Helix Security on Ceres he carries a wallet with a badge. He also has a cellphone with a large visible crack and software that enables him to override most locks on Ceres, and to transform his voice into anyone else so long as a recording is already available. He also wore a Star Helix pin identifying himself as a cop.
For weapons Miller is shown to have a preference for revolvers which plays in to the 'anachronistic old grizzled cop who has been around forever' aura that he cultivated.
While on Ceres Miller is known for his wearing a hat which he jokingly says 'keeps the rain off his head.' even though there is no rain on Ceres. He was given the hat by his friend Sematimba. As a result he gained the nickname of 'le chapeau' (French and Creole for 'the hat'). After his escape from being kidnapped and tortured by Anderson Dawes, he reveals that despite Dawes search of his hat, it still has the memory chip from Julie Mao's apartment hidden in the brim.