When a large amount of people of a similar background are born or sorted into various groups, factions, clubs, or houses for a particular reason. Be it to train or educate easier, to have Urban Segregation, or maybe to take sides in an ongoing war.
This is not a trope to describe a team of four people, but rather four teams of differing kind of person in each. That is, there are multiple groups, clearly different from each other, in which people are sorted into. It is most often described as a single entity/organization that is divided into parts.
- In My Hero Academia, U.A.'s students are grouped based on their field of study. Hero course students are kept in classes A and B, general course students in classes C, D, and E, support classes in F, G, and H, and management classes in I, J, and K. Given the nature of the story, Class 1-A tends to get the lion's share of the focus while the general, support, and management course students tend to fall to the wayside.
- Impractical Magic:Istima is a Magic School that has several 'courts'. Each teaches a different kind of magic. Because students must train their minds and worldviews to enhance their particular magic usage, they tend to develop similar traits. For instance, the rule-bound, very technical magic of the Autumn Court leads to more by-the-book bureaucrats. The Spring Court's collaborative magic produces a collectivist meritocracy and the Summer Court tends to make devious thieves because they have to keep up with everyone else without being able to throw fireballs. Also, in the spring court you can steal other people's magic formula and get rich if you file for a patent before them.
- Districts 1-12 from The Hunger Games. Each person in Panem is born into 1 of 12 districts. When citizens are between the ages of 12 and 18, they are pitted against each other in the annual Hunger Games.
- In Veronica Roth's novel Divergent, Beatrice Prior's society is divided into five factions, each dedicated to the cultivation of a particular virtue. When the factions were formed, however, each gained a negative and a positive trait. The factions are: Abnegation, Erudite, Dauntless, Amity, and Candor. On an appointed day of every year, all sixteen-year-olds must select the faction to which they will devote the rest of their lives after taking an aptitude test.
- The cabins from The Camp Half-Blood Series (Percy Jackson and the Olympians, The Heroes of Olympus, and The Trials of Apollo) at Camp Half-Blood each represent one of the Greek gods and goddesses. Demigods attending the camp stay in the respective cabins patronized by their immortal parents.
- The five cohorts from The Heroes of Olympus, from The Twelfth Legion Fulminata at Camp Jupiter.
- From Harry Potter, Hogwarts School of Witchcraft and Wizardry is divided into four houses, each bearing the last name of its founder: Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin. Houses at Hogwarts are the living and learning communities for its students. Each year a group of a certain house shares the same dormitory and classes. The houses compete throughout the school year, by earning and losing points for various activities. The house with the most points wins the House Cup. Each house also has its own Quidditch team that competes for the Quidditch Cup. These two competitions breed rivalries between the houses, the greatest of which is that between Gryffindor and Slytherin. At the beginning of each school year, the magical Sorting Hat is placed on each new student's head during the Sorting ceremony. The Sorting Hat announces the house the student is to join.
- Disciplines from The Magicians are academic groupings based on areas of aptitude within Brakebills College. The known disciplines are Physical, Natural Magic, Illusion, Knowledge, Healing and Psychic.
- Ars Magica has Houses of magicians within its overarching Order of Hermes, and each house has its own traditions and personality. For example, Flambeau tend to be combat-obsessed pyromaniacs, while Tremere are rigidly hierarchical politicians. Tabletop RPGs had featured Fantasy Character Classes and other Splats since the early days of Dungeons & Dragons, but Ars Magica was one of the first to give these character types reality in the society of the game world.
- Most of White Wolf's games were, in effect, inspired by Ars Magica (above), which was indeed published by White Wolf at one stage, and feature Splats (i.e. factions or groupings) that tend to determine characters' abilities and personalities. For example, Vampire: The Masquerade has Clans, Werewolf: The Apocalypse has Tribes, and Mage: The Ascension has Traditions and Conventions.
- Players of The Elder Scrolls Online have the opportunity to join any of the three factions warring over the Ruby Throne of the Emperor of Tamriel: the First Aldmeri Dominion (represented by an eagle) led by Queen Ayrenn, composed of the Altmer (High Elf), Bosmer (Wood Elf), and Khajiit races; the Daggerfall Covenant (represented by a lion) led by High King Emeric, composed of the Bretons, Redguard, and Orsimer (Orcs); and the Ebonheart Pact (represented by a dragon) led by Jorunn Skald-King, composed of the Nord, Dunmer (Dark Elf), and Argonian races.