The Defenders is at its very best when it lets go of whatever designs it had on being a serious prestige drama and embraces the fact that it's a pulpy cape procedural about a bunch of toughs taking on a supernatural crime syndicate. The Defenders knows that it's a comic book show and it's stronger for it.
There are a handful of ways that The Defenders openly nods to its comic book roots, such as pairing up somewhat random characters like Karen and Trish for no reason other than to have scenes featuring them together, or having certain people such as Misty make uncharacteristic decisions just to drive the plot forward. Of all the comic book-y narrative and aesthetic conventions that are used, the one that stands out most strikingly is the show's lighting and use of colour.
From the very opening shot of Danny battling the Hand in a sewer to the final scene revealing that Daredevil survives the destruction of Midland Circle, there are overt and subtle colour cues carefully placed throughout every frame that tell an important story that runs parallel to The Defender's larger narrative.
Though Daredevil is the only Defender to ever don a full-on superhero costume on screen, all of Netflix's Marvel series leading up to The Defenders has spent ample amounts of time making sure that we, as an audience, associate each Defender with a particular colour palette. In addition to emphasising that all of these heroes actually live in the same city, The Defenders' opening sequence (linked above) also serves as quick visual reminder of which Power Ranger everyone's supposed to be.
Unlike Daredevil, Jessica Jones, Luke Cage and Iron Fist, which kept its players relatively sandboxed off from one another in their respective neighbourhoods, The Defenders affords everyone a degree of mobility that makes this New York City feel a lot more realistic. But rather than acting as if the Defenders have all suddenly discovered the subway system for the first time, the show makes a point of differentiating each character's world from the others by using drastically different lighting and colour correction to signal where we are at any given moment.
When we're in Harlem with Luke and Misty, shots are drenched in Luke's signature bright yellow, whereas scenes featuring Matt in Hell's Kitchen drip in inky shades of red. Jessica's scenes shift with tension between deep purples and fluorescent purples, while Danny's are washed out in a calming mint green punctuated with flashes of gold.
The first few of The Defenders' episodes lean heavily on this storytelling technique almost the point of going overboard with it, but halfway through the series in episode four, the information that the colours are trying to convey shifts in an important and interesting way.
By the time the Defenders all make their way to the Royal Dragon and begin to play with the idea of coming together as a makeshift team, the lighting has begun to function somewhat differently. The first half of the series works in colour blocks that are largely uniform when focused on the characters as individuals, but once they physically come together, each of their themes is present throughout the scenery in ways that would look ludicrous in person, but work wonderfully on the screen.
More importantly, though, the colours in the foreground and background are now operating independently from one another, telegraphing unspoken information about the scene. The bulk of the sequence set in the Royal Dragon involves Danny and Matt explaining just what the Hand is to Jessica and Luke. The foreground lighting, you'll notice, is attuned to that same shade of green associated with with Danny and the Iron Fist while the background lighting and accents of the restaurant reflect the others.
At first glance, it may seem like the colour choices are simply a reflection of the fact that everyone's together, but if you pay closer attention to the individual tight shots of the characters, the lighting come across more like a representation of where people are (mentally) in relation to the main plot. Just after they have entered the restaurant together, Jessica and Luke break off to have a conversation about the weirdness of the mess that they're in, but it's obvious that both of them are simultaneously thinking about other things going on in their lives as it related to the present situation. As Luke asks Jessica if she's all right (bar lit in purple above his shoulder), Jessica's thinking about what she's deduced about Matt and the fact that he's literally just appointed himself her lawyer (red neon light over her shoulder).
This purposeful placement of other characters' motifs in the background of important shots is scattered all throughout The Defenders. As you get deeper into the series, the technique becomes more subtle, fading into the background because the show understands that it's spent enough time teaching us how to interpret this visual language. Later, as the group interrogates Sowande about what the Hand is planning to do, there are multiple moments where Matt purposefully avoids mentioning his history with Elektra, that he knows she's the Black Sky, and what that means for all of them.
Whatever concerns Matt has about the Hand and its interest in the Iron Fist (here represented by the green chairs, which are present, but movable) are moved literally to the background, but not nearly as far back as the splash of red on the warehouse wall, a literally foundational part of the scene and Matt's life.
The worst thing a show like The Defenders, one with so many moving parts and plots to juggle, could do to connect its characters to one another emotionally would be to have them sit down and clunkily talk about their thoughts and feelings to one another. There is a bit of that here and there, but in letting the interplay between colours stand in for a character's headspace, The Defenders does something much more artistically refreshing.
With comics, we've come to expect this kind of emotional exposition from boxes of internal dialogue that only the reader is privy to, but The Defenders manages to give the audience that same kind of intimacy with its characters using only a little bit of colour.