While the archetypal hard-boiled detective might be a bit of a lone wolf, almost all detectives—especially on-screen detectives—need a partner, a team, or at least a sidekick.
The reason for this is fairly practical: if you have more than one detective, or a detective and a foil, then you can add in some exposition by having them explain to each other what's going on, or have the audience watch as they figure it out together, like in the clip below where McNulty and Bunk of The Wire explore a crime scene (video is NSFW for brief nudity and a graphic murder scene):
And, things being the way they are in the world, these supporting roles provide a lot more room for representation of people who are not white straight men. We learned this lesson early, right?
Getting a bit more up to date, we're now in a place where white, straight, cis, able-bodied women are routinely central detective characters. But the supporting cast and partner roles are still needed to open up space for portrayals of bisexual women and women of color, for example, as on a show like Bones. Bones is a police procedural of sorts. The main character is Temperance Brennan, a forensic anthropologist turned crime-fighter, partnered with FBI Special Agent Seeley Booth. RMJ already did a great job of summing up the positive representation of women on this show and some of the ways it is still problematic here at Bitch, so I won't retread the same ground.
The character of Brennan deserves recognition for making some pretty brilliant statements about it being okay to be who you are. See this post at the Hathor Legacy and this one at Echidne of the Snakes for more on her.
But the reason I'm highlighting it here is that the writers build up a team of characters, such as Camille "Cam" Saroyan, who came into the show in the second season as Brennan's superior, and Angela Montenegro, the team's specialist in facial reconstruction and the artsy "heart" of the team.
Astrid's character on Fringe has grown from insultingly slight to being gradually filled out into someone worth watching. Fringe sits in the cross-over space between detective show and science fiction. Walter Bishop is an eccentric, ultra-smart inventor, whose experiments are destroying the universe. In a bid to stave off disaster, the FBI brings him on board into its "Fringe" division to investigate unusual extreme-science events, along with his son (who I can still only think of as Pacey off Dawson's Creek), led by Olivia Dunhum.
But when the team was put together, Astrid was also transferred from the FBI to work in Walter's old-fashioned lab. Although she is a junior agent, it's still unclear why and how she has become stuck as an assistant fetching food for Walter and working in the lab, rather than, *ahem,* investigating crime like every other character—even those not trained to do so. And then there's the running gag about how Walter can't remember her name, as excerpted below:
But this post over at Racialicious gives what's probably the most forgiving possible reading, which fully draws out why she is awesome, and how the character has developed—albeit at an almost glacial pace—into more than the stereotypical super-genius assistant.
Even shows which, viewed from a broad perspective, are frankly offensive, sometimes the partner/sidekick character can provide a respite. I count the 2007-09 two-series show Life in this category. The show was about a white cop who has been wrongly imprisoned for 12 years, then gets released, given a massive settlement which makes him super-rich, and also reinstated to his job in the LA Police Department. Which, let's just say, is a bit of an interesting representation of miscarriage of justice.
Moreover, Charlie Crews (Damien Lewis) is shown with an endless stream of women—not a bad thing in itself, it's just that in the show they're paraded around like his new car, home—portrayed as objects he is basically accruing. Anyway, it was quite a smartly written show all the same, and the best bit for me was his unwilling partner Dani Reese (Sarah Shahi), who acts as a great foil for what an arse Crews was.
Good things about Dani Reese's character; she's sensible, she's smart, she gets to be flawed. The only problem was the inevitable "will they-won't they?" "she hates him but secretly she's falling for him!" dynamic the writers built up between Crews and Reese.
Anyway, what you might notice here is that, even just mentioning three shows, there clearly seems to be a lot more room for diversity in the casting of the supporting cast around the central detective. I feel in two minds about this. If you expand to the supporting cast—well, yes, it smacks of tokenism, but the picture does get better.