For when you have choice over who the protagonist driving the plot at the moment is.
This is for when you can't always say for sure who The Protagonist is, as there are several POV-character choices, depending on where you are in the story. What you can say is that a pool of main (or mainish) characters are likely to be driving the plot at some point. They form a mini-Cast Herd of what, in shorter, less convoluted stories, would be full-time protagonists if their arcs were taken separately. They are not simply a Spotlight-Stealing Squad that thinks it's all grown up[[note]]Although, they can be that, too: it's a free story![[/note]]. And, certainly shouldn't be confused with Day in the Limelight minor characters, although you could argue that what we have is a cast of major characters doing just that. It is the main preserve of Doorstoppers, Long Runners and stories following a sprawling Kudzu Plot with a Cast of Snowflakes. Or, just Loads and Loads of Characters with heavy emphasis on such things as Rotating Arcs, Simultaneous Arcs, Two Lines, No Waiting, Four Lines, All Waiting, Breaking the Fellowship, and/or generalised Let's Split Up, Gang highjinks going on. One character may be the Designated Hero[[note]]or, heck, the Designated Villain, too[[/note]] or the Chosen One of the whole overarching story, and, thus is the theoretical “leader” of the protagonist pool and the others' actions will almost always feed into this main story in some way. Yet, at many points, all fulfil main-character, point-of-view duty for lengthy and vital segments of the plot-focus where the "leader" is either not there at all, or only there in support. Sometimes, these "other protagonists" can even be said to overshadow the supposed main one or two[[note]]Spotlight stealing for the win![[/note]], in many people's eyes. In short, although there may be a traditional main character (or even two or three), they can easily be accused of having bouts of Designated Protagonist Syndrome, rather, while others deal with the actual plot. When a character has suddenly become struck with the Main label for any given section of the plot-arc route, they can be said to be driving the car (a.k.a. the plot focus) the whole pool shares. They might then pull over, get out and let somebody else get in and take the wheel for a bit. Most often, this means they take the bus to somewhere else, while the car continues away. They may then get back in and take the wheel over at some later stage, when the car next pulls up near them. Alternatively, you have several characters in the car who either shuffle back, forth or sideways to become supporting, back-seat kind of characters or even changing roles to become co-drivers or navigators[[note]]in cases of Deuteragonists or more[[/note]] as they spell the wheel together without actually leaving the car at all. When you have cases like this, all are likely to leave the car together, when the next section of road means they have to pull up and let a new lot (or singleton) take over and they hit the bus services together. Or, they may totally rearrange the group, with some staying, and others leaving. Protagonist Carpooling may get confusing, as the characters can run the whole gamut of protagonist tropes, or just by dint of the complex pattern of who gets in and out the car when. The Poolers can include various flavours of Heroes, Villains and Others[[note]]See the Sliding Scale Of Anti Heroes and Sliding Scale of Anti-Villains for when lines get blurred.[[/note]]. It all adds to the fun if done well, a headache if not. For a fun list of things to be on the lookout for in Carpooling Protagonists, look no further than these tropes in a plot: Cast of Snowflakes, Rotating Arcs, Simultaneous Arcs, Let's Split Up, Gang, You ALL Share My Story, Deuteragonist, Designated Protagonist Syndrome, Supporting Leader, Supporting Protagonist, Decoy Protagonist, Hero of Another Story, Pinball Protagonist, First Person Peripheral Narrator, Useless Protagonist, Villain Protagonist, a lot of A Day in the Limelight mixed with Put on a Bus and, last, but not least, the Spotlight-Stealing Squad.
ExamplesAnime and Manga: Point and theme of Baccano!, which deals with storytelling while presenting glorious fun and ass-kickage. The stories are told from the perspectives of several funky individuals, such as Jacuzzi, Dallas Genoard, Isaac and Miria, Eve Genoard, Firo Prochainezo, Luck Gandor, Chane Laforet, Ladd Russo, Czeslaw Meyer and Clair Stanfield, every single one the main character of his story, which is presented as such. All these characters interact with each other, too. In similar vein, the sister series Durarara!! focuses on the interactions and adventures of several residents of the Tokyo district Ikebukuro, with out having a clear protagonist. Naruto: Each and every time you get a party split for whatever reason, you get this. And, boy, do we get party-splitting (although it's more pronounced in the Anime where minor-major characters get more focus, but can still plot-drive to limited extents, even while being Filler). A slightly debatable example: Naruto is the main driver (although Sasuke, for all his faults, is one definite co-driver). Tower of God: Although the star of the story is quite arguably one person (Baam), he's not the only one driving the plot-focus mobile by any stretch of the imagination. At times, we get doses of Agero Agnis Koon (and whichever team of well developed characters he's currently with). Then, there's... uh... the controversial Rachel, Wangnan and those around them who may (or may not) get focus of their own. Baam is the intersecting point who isn't always in the driving seat, not just of the plot-focus, but the plot itself. And, beyond all those, are The Other Stories going on around them all, as well. It's fun! Kubera: A large cast? Check. Many points of focus? Check: we get to see a fair bit of characters without the main one's title name[[note]]pun intended[[/note]] doing their thing. Brillith and Agni (the whole City arc) spring to mind, as well as what can be dubbed "The Sura Sections". Not to mention Yuta (and whatever he's going to get up to next), Ran (ditto) and last, but by no means least, Asha. Literature: The Lord of the Rings: From the splitting of the Fellowship onwards, we get this trope to a T. Roughly two-thirds of a defining Doorstopper devoted to this? Yes. Also the Film(s)... for obvious reasons. Wheel of Time: Ye gads: do you get carpooling or what? What with three main "protagonists" officially whacked into that role via an in-world phenomenon known as ta'veren, you've got the vast herd of others who yank focus out of their graspy little hands at any given minute to go charging down the plot road on their own or even with others. Heck, the Villains get a lot of screen time during which they do some driving! Game of Thrones:OK... tell us (please, do!)... who the main Hero (or, heck, Villain) actually is. Cake for anybody who can. The number of characters with focus is unbelievable and even the nasty ones have redeeming qualities that are essential to the plot direction. And, when you add the plot-strands together, it just gets worse. The TV Series gets this as well, even if it does try for some Adaptation Distillation. Webcomics Homestuck. Full stop. Order Of The Stick: With the Order themselves clocking in at six, add all of Team Evil for Villain Protagonist slots at any time, stir in with lesser, but no less plot-driving main-like characters in almost every major arc. Oh, and the Linear Guild.