Descent Into Darkness Song
You know how sometimes you're listening to a pretty chipper song, and you think it's gonna stay that way? Sometimes it doesn't. That's what you call the descent into darkness. A Descent Into Darkness Song is a song that changes its tone, slowly or quickly, into something much darker. The evolution of the music can involve modulating from a major key to a minor one as shorthand for a darker style. If there are words which are consistantly upbeat, there may be Lyrical Dissonance at the end; the inverse is also true if they're depressing throughout it. If in a musical, it can be a positive song that becomes sinister when the heroes leave. If the song is wholly cheerful but later sung tragically, you have a Dark Reprise. This can be a form of Villain Song.
- The Once-ler's Villain Song from The Lorax gradually becomes darker as the song goes on, starting in his casual worker clothes with his acoustic guitar, to wearing a flashy new business suit, to making huge, polluting factories, to not caring if "a few trees are dying", while you see him destroying said trees with the soundwaves from his new electric guitar, and carelessly hacking down every tree left and right while the forest creatures run for their lives. Not only does the song get so much darker, his voice gets a distinct malevolent echo at the end.
- "The End", by The Doors, famously starts off as a ponderous musing about the nature of finality. However, eventually the imagery shifts into describing a masked killer grappling with the desire to kill, and then killing, his own parents. Afterwards, the tempo builds up to the end, creating a mesmerizing climax. Which, incidentally, makes it the perfect song to be used to bookend Apocalypse Now—a descent into the evil that lurks in the human heart.
- Bill Bailey has an OTT Obsession Song that starts a bit depressed. Only a bit, mind you. Then it goes serenely upbeat and joyous, followed by being unbelievably angry and unhappy.
- The Flight of the Conchords song "Petrov, Yelyena, and Me": The lyrics get more disturbing as the singer catches on that Petrov and Yelyena are eating him piece-by-piece.
- In South Park: Bigger, Longer & Uncut, the "Little Boy, You're Going to Hell!" song that plays when poor Kenny, well, goes to Hell.
- Helen Reddy's hit Angie Baby (written by Alan O'Day) which starts out okay, being about a "touched" girl who uses her radio to keep her company. It soon turns to the girl having to be removed from school and eventually to the subject of potential rape and the vague aftermath that results in the disappearance of the young man, leaving the listener to wonder whether he was killed by Angie with something maybe worse (since Angie has "a secret lover who keeps her satisfied") or she's just imagining him still there.
- Helen Reddy and singer/songwriter Alan O'Day (Undercover Angel) eventually revealed the truth : Angie was a Reality Warper, and the boy with 'evil on his mind' was not the first she shunted away for her pleasure.
- Several songs by Stephen Lynch. "Superhero" starts with describing various superheroes kids might want to be before turning into a diatribe against his unfaithful wife who now lives in Hawaii with a doctor, dumping him with three kids and no job. For those interested - song here.
- 'Princess of December' from UFO Princess Valkyrie. Starts out as a romantic song of eternal love and devotion, sung by the titular Valkyrie, only for it to be hijacked halfway through by her Shadow Archetype, Valkyrie Ghost, who turns it into a heart-wrenching song of loneliness and despair. It's one of the first hints that the Dark Valkyrie is actually a tragic figure, rather than the out-and-out villain she first appear to be. You can hear it here.
- "More Gun" from Meet The Engineer? It starts off as a calm campfire song but VERY quickly turns harsh and ends up sounding like a western duel song. If you are interested, here it is.
- The Legend of Zelda: Majora's Mask has the Clock Town theme. It starts out rather upbeat enough, as the town is mostly going about its business and the townspeople blissfully ignorant that anything's wrong. Sure, the moon is up there glaring at them, but it's way out there. What's it gonna do? The next day, the moon is demonstrably closer than its original position, and that night, closer still. The music is slightly darker to accomodate. Then, by the third day, the music is outright apocalyptic, since the townspeople have all but fled or given up in terror, and the moon is so close it looks like it could cleanse the planet with one strong snort.
- The use of this trope is flat out perfected in The Legend of Zelda: Twilight Princess, for its Hyrule Castle theme, which is the final dungeon of the game. It starts off soft and majestic, with a revision of the Hyrule Castle song from A Link to the Past. As you progress through the dungeon, however, the song gains a bassline that may sound...a bit familiar. Later, the bassline is seemlessly expanded into Ganon's theme, which is perfectly overlaid onto the Hyrule Castle theme. From that point on, Ganon's theme slowly takes over, becoming louder and more pronounced while the Hyrule Castle theme becomes softer and more subtle. By the time you're in the stairway before the final battle, Ganon's theme has completely taken over.
- In Friendship is Witchcraft Pinkie Pie's orphanage song does this. It begins as a happy song, but then Pinkie starts singing about how unworthy she is.
- Still keeps its deceptively happy tune though.
- "I Believe" from Spring Awakening has its tone darken as the two leads transition from kissing to ambiguously consensual sex.
- An instrumental example, Rude Awakening, No. 2 by Creedence Clearwater Revival starts out mellow but becomes more and more spooky as the song goes on.
- The Hunchback of Notre Dame, Frollo's "Hellfire" song counts as a Dark Reprise of "Heaven's Light", but it also counts alone as this trope. A sacred chant leads into the song, With composure, Frollo sings to the Virgin Mary, "You know I am a righteous man..." and then the song gets darker as he sings of how desire for Esmeralda tempts him. The accompanying chants turn ominous, and Frollo pictures himself condemned. He concludes: "She'll be mine or she will burn!"
- In Turnabout Musical, Phoenix's 'Reawakening' song starts out as upbeat as could be, as he's feeling good about his victory in court. It turns downright heartbreaking when he returns to the office to find his mentor murdered.
- The song "Handlebars" by the Flobots starts with a young boy innocently bragging "I can ride my bike with no handlebars." As the song continues, the boy grows up and his statements become darker and more grandiose, ending with "I can end the planet in a holocaust."
- In EarthBound, the infamous Final Boss theme "Pokey Means Business" (better known as Gigyas's first theme) starts off predictable and vaguely melancholic, then abruptly switches to frantic and disturbing.
- From Portal 2, the track 'I AM NOT A MORON!' fits this trope to a T: it starts out with triumphant, happy electronic tones, but halfway through it switches to a much more sinister tone played by brass and strings, culminating in a dark reprise of the turning point in the track, combining both orchestra and electronic music, ending in a much different place than it started.
- The Vocaloid song "Wordplay" in the Evillious Chronicles by mothy. It begins with the singer talking cheerfully about the first time she learned of the world, friendship, and love. Then it slowly cycles through the first time she learned of pain, punishment, lies and evil, with the video getting darker and grayer as well. It's implied this is the same person who becomes a Mad Scientist in the later song "Moonlit Laboratory".