Sometimes, it takes paragraph after paragraph to get an idea on what kind of a person you're dealing with. Sometimes characters are so complex, so deep and nuanced, that an entire episode is devoted to some esoteric part of their back story.
And sometimes you can figure out everything you need to know about someone as soon as they get into their car. Taste in music, especially when it's out of the ordinary, can tell you more about a character than a monologue or flashback ever could. A little well-placed Mozart or Chopin lends an outwardly simple-minded individual a bit of mystery and depth. Someone listening to The Beatles, even though it's 2237, and they're on Mars? Safe to say they're a bit old-fashioned. And if they listen to '80s rock, they may become a victim of AC/DC Characterization...
Music can convey a lot more than just what's in the lyrics, so matching this song with that character, while a bit of a cheat, is a fantastic way to convey a lot about a character in not a lot of time. This also does wonders to convey a deeper side to a character that can easily be considered one-dimensional. A mousy librarian suddenly takes on a wilder angle when their iPod is blaring Joan Jett and the Blackhearts.
This trope does not refer to a character's theme song, if they have one. This refers to diegetic music, often called Source Music, where the other characters can hear it.
- Monsters University: While Mike takes the guys to Monsters Inc., Squish's mom - a sweet and cheery person - stays in the car to "listen to my tunes", after which the first couple of split seconds of Mastodon's "Island" can be heard.
- A Goofy Movie. Early on, Max and Goofy have a Dueling Banjos moment over the radio between Goofy's 'High Hopes' and Max's acid rock. Not only does this show a lot about each character, it highlights the generation gap between them, all without saying an actual word.
- All Dogs Go to Heaven: When Charlie meets up with Carface after escaping from the pound, Charlie turns on the radio so he can listen to some jazz while they talk, while Carface turns it off so they can just talk business. They go back and forth until Carface has enough and pulls out the knob to turn off the radio for good.
- Reservoir Dogs. The pairing of Mr. Blonde's Torture Porn with 'Stuck in the Middle With You' by Stealers Wheel helps to showcase how seriously he doesn't take the situation.
- Star Trek. In the J. J. Abrams reboot, our first encounter with a young James T. Kirk is him hanging up on his step-father in favor of blasting the Beastie Boys' "Sabotage" (a song that In-Universe is a hundred-plus years old) over the radio, establishing his disregard for authority (and a certain degree of love for Good Old Ways, even if they clash with Federation standards) even before the character says a single word. The detail about "Sabotage" being so old it's considered "classic" (and Kirk loving it) gets a Call-Back gag on Star Trek Beyond.
- Star Trek: First Contact used Roy Orbison's "Boogie Oogie" on the jukebox and Steppenwolf's "Magic Carpet Ride" during the first flight to convey Zefrem Cochran's old-fashioned personality.
- Marvel Cinematic Universe:
- Iron Man: Tony's Establishing Character Moment involves rolling in a Humvee as part of a military convoy, listening to "Back in Black" by AC/DC.
- Iron Man 2. After Tony Stark's birthday party is ruined by an Iron Man suit-wearing James Rhodes, Tony requests for the DJ to play Queen's "Another One Bites the Dust" as a way to show he doesn't take Rhodes' threat even remotely seriously.
Tony Stark: Give me a phat beat to beat my buddy's ass to.
- Earlier in the film he enters the Stark Expo playing "Shoot to Thrill" by AC/DC, which will be repeated in...
- The Avengers, when he hacks the Quinjet's PA System before flying in to confront Loki in Germany. No matter where he goes, he has to create a spectacle. In a more subtle example, he wears a Black Sabbath shirt after that.
- Guardians of the Galaxy: At the beginning of the movie, Peter Quill's on a dead world and enters a ruin that wouldn't seem out of place for an Adventurer Archaeologist... and then he turns on an old Walkman and starts dancing through the place to "Come and Get Your Love" without a care in the world, even kicking away some of the local vermin. The movie's trailer used "Hooked on a Feeling" to give the same sense of irreverence. Peter's Walkman and mixtape of classic pop songs are reminders of Earth, and specifically his mother, who had died from cancer the night he was abducted.
- Guardians of the Galaxy Vol. 2 continues it, turning "Brandy" by Looking Glass into an Expository Theme Tune for Meredith Quill's affair with Ego the Living Planet. Ego, of course, misses the point that the song's about Brandy, not the sailor. Rocket has also mellowed out a bit since the first film, represented by how he's developed a taste for Peter's music; he creates a Moment of Awesome when he, Yondu, and Groot decide to ruin some mutineers, and Rocket elects to do it to the tune of "Come a Little Bit Closer" by Jay and the Americans.
- The Silence of the Lambs. While in the prison cell in Tennessee, Hannibal Lecter listens to classical music just before his prison break. This tells the audience that even though he's a psychopathic cannibal, he's still Wicked Cultured.
- Three Kings. One of the soldiers wants to listen to heavy metal music while going into battle. Another soldier criticizes his musical choice and suggest they go into battle with something soothing to calm their nerves and plays an easy-listening song, showing a definite personality clash.
- Transformers. Bumblebee, the first Transformer our protagonist meets, actually has no real voice capabilities, and instead does all of his vocalizations through playing songs on his stereo. This is the trope cranked Up to Eleven.
- The movie I, Robot starts with Stevie Wonder singing "Superstition" to wake up Detective Spooner. This certifies Spooner as retro, showing at least one reason for him to dislike robots. The song also foreshadows his journey through the movie. In the same vein, the song that plays when the scientist gets incredibly flustered by the retro cd-player: 'Somebody Save Me'...
- Hilariously subverted in the opening of Office Space, where a character listens to bad-ass rap music on his way to work, but then is shown to get nervous about a harmless street vendor approaching his car.
- 10 Things I Hate About You. Kat Stratford is introduced blasting Joan Jett's "Bad Reputation" in her car.
- Whip It. Razor drives up playing "Hold On" by Wilson Phillips in his Dune Buggy, wearing clothes that mark him as a refugee from The '80s.
- "Hold On" also makes an appearance in Harold And Kumar Go To White Castle on a tape in a truck belonging to a group of supposed "extreme" sports enthusiasts signifying that they're all talk.
- The family in Funny Games listens to opera music in their car which establishes them as being of the middle-class. The villain duo listens to Death Metal.
- Played with in Mr. & Mrs. Smith (2005) when Mr. Smith, a badass up to this point, sings along with Air Supply in the car, much to Mrs. Smith's chagrin.
- The Martian and its film version provide a third-person version of this Trope: after being stranded on Mars, the only music and TV Mark Watney has available is that which is on a portable drive that tough-nut Commander Lewis left behind during the evac. The drive is full of nothing but Disco music (like ABBA and Donna Summer's "Hot Stuff" (which Watney sarcastically calls the least Disco song Lewis had on the drive)) and episodes of Seventies shows like The Dukes of Hazzard and Happy Days. The moment he manages to contact Earth, one of his first messages is a request for NASA to figure out a way to beam him music — something, anything, but Disco.
Response from NASA: The bandwidth is too low, sorry. Enjoy your boogie fever.
- Alex in A Clockwork Orange and his love of classical music, especially Beethoven... there are even hints this mystifies people who would expect someone intelligent enough to apprciate such music would be less anti-social.
- Armada: Zack Lightman's go-to music to listen to while playing the titular game is "Raid the Arcade", a playlist his late father used to listen to while gaming. If anything sums up Zack's obsession with the father he never had a chance to know, it's that. His father, not as dead as Zack believed, later blasts Run DMC over loudspeakers to piss off and distract the straight-laced Admiral Vance, nicely summing up Xavier Lightman's disrespect for authority.
- In Percy Jackson And The Olympians - specifically, The Titan's Curse - Thalia criticizes Grover's choice of music for the dance at the beginning. She prefers Green Day, a band that Grover has never even heard of. It contrasts their personalities pretty well.
- This is a staple of Seanan McGuire's work. Music is featured often in-universe, and Seanan also often includes as an afterward a list of music which she associates with the book and its characters.
- Defiance. Our first encounter with Nolan and Irisa, the two main characters of the show, has an awkward silence broken with Nolan turning on the radio, only to hear Johnny Cash and June Carter singing 'Jackson', which, in the year 2046, is more than a bit country and old-fashioned.
- This show is a bit of a running example. Given that Sam and Dean drive state to state and coast to coast with nothing but a stack of classic rock tapes (Tapes!) to listen to, it provides both a soundtrack for the show, and an insight into the characters.
- In an episode where Dean is dead, we get insight into Sam by his choice of music when Dean isn't around to exercise his veto power. In "Lazarus Rising", Dean discovers that the tapes have been replaced by an iPod and the classic rock by Jason Manns. When Dean comes back, he's not pleased.
Dean: I told you to take care of her, not douche her up.
- Star Trek: The Next Generation:
- Commander Will Riker's love of jazz shows a softer, easier-going side than his military bearing suggests.
- At one point in "Suddenly Human", Picard walks past the guest quarters where the Talarian-raised human teenager Jono is staying, and hears this blasting in the room. Jono's enjoyment of "alba ra" seems to signify he's a typical teenager; Picard hating it and ordering Jono to turn it off shows that Picard is not good with children.
- Picard's own musical tastes mainly run to classical, in keeping with his characterization and background as a bourgeois, well-educated man.
- Jekyll establishes Hyde's personality through his fondness for Disney songs.
- Kamen Rider Double: Shotaro fashions himself a Hardboiled Detective, but frequently undermines himself and winds up what the other characters call "half-boiled"; one of the ways this happens is that he not only listens to Idol Singers but sings along.
- The second season of Millennium saw Frank Black's character being fleshed out through details like his love of Bobby Darin.
- Breaking Bad does this a lot. Oftentimes doubles as foreshadowing, as the lyrics or titles of the songs tend to somehow be relevant to events later in the episode.
- In an episode of The Mentalist Jane inducts that the victim did not drive himself out into the woods and commit suicide but rather someone killed him and drove him out to dump the body, because the radio in the vic's pickup truck was tuned to a Hard Rock station and the victim was only interested in the classics.
- The Office (US) has Dwight's classic rock fixation, especially the way he hypes himself up before a challenging situation. "Kickstart My Heart" seems to be a favourite.
- In the Miami Vice pilot, Tubbs looks through Crockett's music collection and finds George Jones, Jimmy Buffett, Dickey Betts, and Waylon Jennings.
Tubbs: Where does Crockett get his music? Sears and Roebuck catalog?
- Halo: Combat Evolved: The Apocalyptic Log that Master Chief finds indicates that Sergeant Johnson has a love of classic rock not shared by most of his troops.
- Medal of Honor: An early scene in the 2010 game start with the POV character riding shotgun in a truck through an Afghan village, the driver a tanned bearded fellow in local attire... who immediately reveals himself as an American soldier by complaining about your character's preference for local music as he shuts off the stereo.
- Grand Theft Auto games sometimes use this by having cars preset to a particular music station (i.e., the Mafia have the station that plays a lot of Italian operas).
- Metal Gear Solid V's Quiet is unable to speak, but spends a lot of time listening to cult 80s electronic pop music.
- In the Alice Isn't Dead episode "Alice," the long haul trucker Narrator briefly sings along with Weezer's "Say it Ain't So," a story of Parental Abandonment and following in their footsteps by replicating their addictive behaviors. The Narrator proceeds to explain, via audio diaries, how she struggled to admit that her wife Alice had suddenly left her, and upon discovering that Alice was secretly caught up in some sort of cross-country spanning Conspiracy, abruptly quit her job and started investigating, by travelling cross-country as an employee of one of the companies involved.
- Lovely Little Losers: In the interviews for the cereal challenge, Ben asks Balth and Peter each what their favorite song of the moment is. Balth mentions (or, rather, Ben mentions for him) "Lay and Love" by Bonnie "Prince" Billy. Peter singles out "Glare" by Sheep, Dog & Wolf. At a time when Balthazar is being uncommunicative about his feelings, and Peter is outright lying, the songs give an idea of what's actually going on in their heads. (Peter's headspace is, apparently, terrifying.)