This is my understanding of Worm setting, I’m trying to mostly follow canon as I know it, so expect some fanon mixed in.
The point is to quickly bring someone up to speed to read Worm fanfiction where canon knowledge is assumed.

Split in two parts - first one is a quick overview of the general events, places and people, and second one - the spoilers, things that if characters in the book knew earlier or at all it would have changed everything immensely for everyone.

Overview

Scion and powers

The main events start happening around 2011.
Around 30 years before that, in the 80s, a naked golden man appeared somewhere over the ocean.
This is the divergence point, before that it’s assumed the universe has identical history to our own.
So, people on the nearby cruise got closer and touched him - they became the first Parahumans - humans with random superpowers.

Since then, it was noticed that a lot of people (something like 1 in 5?.) have what’s called Corona Pollentia - a benign brain tumor that indicates that you can become a parahuman. Under extreme mental distress (commonly referred to as the worst day of your life) people undergo a trigger event - they gain a random-ish superpower that may or may not help them. This also results in appearance of Corona Gemma, a second brain tumor that’s believed to be what allows parahumans to control their powers.

Scion disappeared, but later began to fly around the Earth and do random heroic acts with no sense of priority - one moment he picks up a kitten from a tree, next moment he stops a wildfire, etc etc - but if the wildfire was right next to the kitten he might’ve ignored it.
He’s very hard to track, and he does not seem to do anything other than this - no sleep or other distractions, constantly flying around like that for years.

Powers are officially split into 12 different categories - they’re intended to be threat levels, meaning what kind of response the PRT (later about them) should mount against person wielding such a power, but of course this turned into a dick-measuring contest (esp. in fanfiction).

The categories are (copied from wiki):

CategoryDescription
MoverAn ability that grants a cape enhanced speed or mobility
ShakerAn ability with an area of effect
BruteAn ability that grants a cape enhanced strength or durability
BreakerAn ability that allows a cape to shift into another state
MasterAn ability that allows a cape to control others or create minions
TinkerAn ability that allows a cape to create or alter devices with futuristic technology
BlasterA long-ranged, offensive ability
ThinkerAn ability that focuses on information gathering
StrikerA melee/touch-based ability
ChangerAn ability that allows a cape to alter their form or appearance
TrumpAn ability that allows a cape to manipulate powers in some capacity
StrangerAn ability that focuses on stealth and/or infiltration

They are accompanied by a number from 1 to 10, with something like 12 being reserved for ultimate crazy shit.
So “Brute 1” is like someone who’s twice as strong and/or tough than a normal human, and “Brute 10” is literally indestructible, superman-level
(Endbringers are Brute 9 I think?. Alexandria is Brute 8, etc).

Tinker is an unusual thing - so tinkers are (mostly) baseline humans, yet they are able to produce tinkertech - crazy bullshit futuristic technology that is also non-replicable in most cases, only the tinker who made it (and maybe other tinkers with adjacent specializations) can understand, fix and maintain their tech.

Endbringers

Around 10 years after that, 3 creatures of incredible power appeared one by one and started attacking and basically destroying cities on a schedule - once every 3 months or so - they are called the Endbringers.

  • The first was called Behemoth - besides common endbringer physical size, strength and durability he has powerful dynamokinesis - he controls and redirects energy, irradiates everything around him and has a “kill aura” - a radius around him in which most (para)humans just fuckin’ explode.
  • The second is Leviathan - water-based and very fast, has massive hydrokinesis, causing tidal waves. Sank the island of Kyushu (a huge-ass part of Japan) causing deaths of millions and displacement of tens of millions.
  • The third is Simurgh, also called Ziz and the Hopekiller - the only one that’s always visible as she usually flies in high orbit (compared to Behemoth somewhere in earth magma and leviathan somewhere in the oceans), she’s a telekinetic but most importantly she’s a very powerful precognitive - she sees the future and sets up chains of events. She also has a Scream - a sound(?) she produces that drives people mad when near her which plays into her plots, she basically makes time bombs out of people. When she attacks a city and people are exposed to the Scream for too long the entire cities are walled off (if not nuked) just to contain mad survivors.

The only guaranteed way to stop them is either do do enough damage that they actually retreat, or they might retreat after their “objective” (usually very bad for civilization) is achieved, or to stall them long enough for Scion to appear - he can do enough damage to drive them off immediately - but there’s no way to contact him and he does not immediately “notice” and endbringer attack.

International groups

  • There is the Triumvirate - top 3 heroes of the Protectorate (more about it later). They participated in all or nearly all endbringer fights.
    They are:
    • Legend - official leader of the Protectorate, he can fly pretty fast, has enhanced vision (just can see far and clear), can turn into light - which both makes him travel at the speed of light aka very fast and heals any injuries, although all of that is inconsistent and maybe fanon. His main power is shooting lasers which both can curve (like Darkseid’s) as well as have any number of effects - freezing rays, heat rays, concussive rays, etc etc.
    • Alexandria - her body is frozen in time making her (almost!) completely indestructible. Super-strong (hundreds of tons), fast flight. Also has some form enhanced cognition, a Thinker. Immune to mind control including Simurgh scream. Basically superman without laser eyes.
    • Eidolon - his power is to have any 3 powers of his choosing. Using the same power for a while makes it weaker and switching powers takes a bit of time. But generally he’s considered the strongest parahuman after Scion.
    • (dead) Hero - was an incredibly powerful tinker, friend of the above three, but died to Slaughterhouse 9 (more about them later) in the past.
  • The Guild:
    A Canada-based international hero group that usually deals with S-class threats around the world.
    Only two members got any mention, those are:
    • Narwhal - the leader, a tall woman with a power to precisely control force fields. Unlike most powers, hers is not Manton-limited.
      Manton limit is what “prevents users of powers from hurting themselves”, usually used to describe arbitrary power restrictions that “balance” the powers. For example a “normal” force-field user cannot create force fields inside of people to kill them instantly - Narwhal is a rare case that can. Often Manton limits are what separates living beings from matter (can telekinetically move rocks but not people, or people but not rocks), or other people from the person having the power.
    • Dragon - a world-renowned tinker, she works on reverse-engineering tinkertech.
      She creates and sells the containment foam to the PRT - a foam that can hold most parahumans unless they’re Alexandria or like a teleporter, and is breathable.
      Also, but that’s fanon, she’s the reason the world of 2011 has smartphones and whatever.
  • Strider - an independent planet-wide teleporter that can teleport groups of people, he’s very useful to bring people to endbringer fights.

Taylor’s backstory

Back to 2011, the protagonist is Taylor Hebert, a 15-soon-to-be-16 year old girl in highschool. Her father is Danny Hebert, a hiring manager at the Dockworkers Union, her mother Annette Hebert was a Literature professor who died 2-3 years prior in a car crash while on the phone with Taylor. Because of that death they’re both pretty depressed, Danny is withdrawn.

Taylor goes to the Winslow high school - generally regarded as shit school and gang member recruiting ground, as opposed to Arcadia - a cool clean expensive school that is infinitely better.
In school, Taylor is severely bullied by three girls - Emma Barnes, Madison Clements and Sophia Hess.

Emma was her childhood best friend, Taylor went to Winslow to be with her, even though she had good grades to go to Arcadia.
After her mother died, Taylor cried for a week and Emma was here for moral support.
However, after she went to a summer camp 18 months ago Emma turned on her, became friends with Sophia and they started bullying her with increasing severity.

After she came back to school after the winter break they have locked her into her locker filled with “used feminine hygiene products” that have been rotting there for the entire winter break, and somehow she spent at least an hour(?) there, kicking and shouting and begging to be let go.
This was her trigger event - her power is precise and absolute control over insects in a radius of a city block or two(?).
She decided to be a hero, spent 3 months preparing - mostly just making herself a suit from black widow silk, which is like super strong (5x the steel? comparable to kevlar except way lighter?).

On her first night out she heard Lung, the leader of one of the parahuman-led gangs, preparing to “kill some kids”. She fights him, almost loses, stings him a bunch.
The kids turned out to be of comparable age to her, they are the Undersiders - a small-time gang that does robberies and getaways mostly.
Armsmaster, one of the biggest local heroes, comes responding to Lungs rampage and sedates him with a specialized tranquilizer - it dulls Lung regeneration which doesn’t play nice with tons of venom she injected and later will be a contention point, as Armsmaster convinces Taylor that he should take credit for Lungs defeat.
Anyway, he’s kind of a dick, she later talks to Undersiders who thank her for help with Lung - they stole from him and he was getting them for that.

Later she tells Armsmaster that she’ll join Undersiders and be undercover, because it turns out they are backed by a mysterious boss. He’s still a huge dick.

Now, a little (hah) detour for:

Brockton Bay groups (good)

  • PRT (Parahuman Response Team) ENE (East-North-East):
    They are like SWAT for parahuman-related crimes and incidents. Notably it’s against their rules to have any parahumans.
    Only notable person is Director Emily Piggot, the leader of the “good guys”.
    She’s very hard, and wants the BB to prosper, yet PRT is strapped for resources and she barely manages to “keep the status quo”.
    She’s biased against parahumans, doesn’t trust them etc. etc. to her detriment(!) - she has a kidney trauma from her past that requires her to undergo regular dialysis and she doesn’t accept parahuman healing.

  • Protectorate ENE:
    The good guy parahumans, directly subordinate to the PRT.
    Consist of:

    • Armsmaster - the leader, is a tinker, specialization is optimization/miniaturization. Works with Dragon a lot.
    • Miss Militia - her power is creating any kind of weapon with infinite ammo, kind of like Green Lantern without flight, strength or durability and only makes guns.
    • Dauntless - generates a “charge” every day, that he can put into items, empowering them to be kind of like magic artifacts. A single charge does little, but they stack - at the very least has boots that let him fly, big force-field shield, and a lance that shoots powerful lightning
    • Velocity - discount flash, can “enter the breaker state” that speeds him up, no crazy speeds, like 10 to 20 times speedup? Barely can be fast enough to be invisible by human eye. The big downside - the faster he is, the less he can affect the world around him, so at speed he hits like a baby. Also cannot carry much, the breaker state ends at very short distance from skin.
    • Assault - can absorb and redirect kinetic energy, is a jokester.
    • Battery - when standing still can “charge up” and get bursts of super-speed/super-strength. Commonly punches Assault (who’s also her husband?.) to charge him up, they’re a good combo.
    • Triumph - very recent Ward graduate, can shout (“roar”) sound blasts with some effects maybe?. Don’t really remember, but sounds pretty lame.
  • Wards ENE:
    A “junior division” of the Protectorate, teenagers with powers who joined the government, mostly because their parents made them lol?. Also for protection from gangs, as gangs want all the parahumans.
    (almost) All of them go to Arcadia, which has special half-days specifically so the Wards can attend in secret.
    Consist of:

    • Aegis - can fly and also got “adaptive biology” - if his heart is shot his liver will pump blood, eyes gouged out he will see with his skin, pretty survivable, can live through decapitation (fanon?)
    • Vista - young (12-13 years old), but very powerful (Shaker 9) space warper, she can squish and stretch space.
    • Clockblocker - by touching an object (including people) can freeze it in time for a random amount of time - something like 30 seconds to 10 minutes. Is also a jokester, managed to get his name by shouting it out during his announcement when joining the Wards.
    • Kid Win - tinker, did not figure out his specialization yet (it’s ), has dyscalculia (which is like dyslexia but for comprehending numbers and math) - which is ironic and is a huge drawback for a tinker.
    • Gallant - pretends to be a tinker too, but actually his rich family pays off Kid Win to maintain tinkertech armor, his ability is to sense emotions (as colored auras around people, works through walls) and to shoot “emotional blasts” which affect peoples emotions and punch them a little - pretends that those blasts are part of his tinkering too.
    • Shadow Stalker - can turn into a “shadow” that can pass through walls and glide weightlessly. Uses a crossbow, weak to electricity.
    • Browbeat - who?
      But seriously, he’s like never mentioned, the newest Ward (Vista being the oldest, despite her age), his powers are self-biokinesis (makes himself buff) and very-close-range telekinesis (adds even more to strength).
  • New Wave:
    A group of independent heroes who decided to uncover their civilian identities for some stupid reasons nobody cares about and one of their member was shot in her sleep by some gangster. Their kids are very thankful for inability to have a calmer life.
    Members:

    • Carol Dallon aka Brandish - can create melee weapons from solid plasma, and can also turn into a football sized ball of similar plasma for protection, although she is useless in ball form. Works a cape lawyer. A huge bitch.
    • Mark Dallon aka Flashbang - can create bouncing orbs that explode with some effects (so flashbang or a normal grenade). Suffers from clinical depression and doesn’t do anything, totally apathetic.
    • Sarah Pelham aka Photon Mom Lady Photon - flight, energy blasts from hands, energy shields. She and Carol are sisters.
    • Neil Pelham aka Manpower - close-range electromagnetism, mostly giving himself strength and durability.
    • Crystal Pelham aka Laserdream - their daughter, college-age, power similar to mother except lasers are stronger and shields are weaker.
    • Eric Pelham aka Shielder - son, power again similar to mother except lasers and flight are shit, but shields are powerful.
    • Victoria Dallon aka Glory Girl - daughter of Dallons, has pretty strong flight and durability - the durability is achieved by a shield which can break from a bullet and return in a second or two, but until it breaks she’s invincible, can take a single hit from anything.
      Another power she has is an emotional aura, making people around her either fear her or adore her - she has weak control over it.
    • Amy Dallon aka Panacea - adopted(!!!) daughter of Dallons, can “heal” everything except the brain by touching a person. Stressed and depressed because she volunteers a lot at hospitals and doesn’t think it’s enough, Carol is a bitch because of.. adoption, and some other reasons.

    The last two are important as they take up significantly more screen time both in Worm and in all of the fanfics.

  • The only mentioned rogue (neutral, tries to use powers to make money and not fight) that I remember and that gets any screen time in fics/original is Parian - can telekinetically control threads and cloth, set up a fashion shop on the Boardwalk, does puppet shows for kids.

Brockton Bay groups (bad)

  • The Undersiders:
    Do smash and grab, mostly from big gangs, never target any civilians, each member has an okay-ish sob story of how they came into crime.
    Members:
    • Grue - big muscular black guy, his power is creating huge amounts of unnatural smokey darkness that completely blocks any form of vision, radio signals, most of sounds. He can see through it. It interferes with Shadow Stalkers ability and she fuckin’ hates him for that.
    • Regent - feminine pretty boy, his powers is making peoples limbs twitch and spasm, kinda meh but he’s sandbagging. Lazy, apathetic sociopath, hedonist.
    • Rachel Lindt aka Bitch/Hellhound - a butch young woman, her identity is public because she’s wanted for (accidental) murder during her trigger event. Power is turning dogs into giant lizard-like monsters, enhancing them - this is reversible. She does not control them and has to train her dogs. Power messed up her head and she’s antisocial, “understands dogs way better than people”. Bitch is her preferred name, but the PRT calls her Hellhound for PG reasons.
    • Tattletale - high-level Thinker, her power is basically being BBC Sherlock Holmes - deducting literally all the info from tiny little details, sometimes she gets information like out of nothing. Can get wrong conclusions.
  • Uber and Leet:
    Two villains, usually harmless, they style their various heists and so on with a video game theme.
    • Uber - big muscular guy, he is “an expert in any skill” - probably he switches between skills? It’s a bit vague, don’t remember.
    • Leet - commonly regarded to as a loser, he is a powerful tinker, he can “build anything once” - after that if he builds things similarly to whatever he already built the chance of explosive failure rises. So his tech is known to be unreliable and explode often, naturally.
  • Circus - independent villain, smash and grab, their powers are a bit vague, enhanced agility, hammerspace (a personal subspatial pocket to store shit), weak pyrokinesis (throwing fireballs).
  • Faultline’s Crew:
    A group of mercenaries, do jobs for money across the country, their point is that they don’t do jobs in Brockton Bay, so they are left untouched.
    They (unofficially?) own the Palanquin night club.
    Members:
    • Faultline - can create big expanding cracks in things, “fault lines” - big enough to topple buildings and/or escape.
    • Labyrinth - reality warping. Shaker 12, controls reality in a block or more radius. However, the control is limited in that she “brings other worlds here”, and she’s mentally distant most of the time, they basically care for her.
    • Spitfire - well, spits fire - a very flammable liquid that’s on fire, and also is immune to fire.
    • Gregor the Snail - a case 53, meaning a cape whose powers warped their body. A big and wide man with translucent skin and shell-like warts. A bit of enhanced strength and durability, can generate and throw slime with a few effects.
    • Newter - another case 53, looks like a lizard man, again a bit of agility and durability (and a tail). His bodily fluids (sweat, spit, blood etc) are a powerful hallucinogenic without side-effects besides knocking people out and giving then a high. Maybe fanon, but gives out the high to Palanquin visitors.

Brockton Bay groups (ugly)

  • Empire 88
    Actual white supremacist neo-nazi gang, the reason Brockton Bay is called the neo-nazi capital.
    They have the most parahumans of all other groups, a shit ton of normie gang members and a bunch of nazi supporters in like the police and shit.
    Members:
    • Kaiser - can create metal blades (or just metal?) in his sight, usually generates intricate armor around himself.
    • Purity - turns into a blindingly white figure of light, can fly and shoot very powerful blasts (Blaster 8, can level a building if not an entire block). In the last year (after birthing a child) tries to “cut ties” with the Empire and maybe even become a hero (ha-ha).
    • Hookwolf - turns into a wolf-shaped mass of metal hooks and blades - actual mass-murdering psycho, very strong and very dangerous.
    • Stormtiger - aerokinesis, flight, “air claws” in close range and slicing blasts.
    • Cricket - ultrasonic sonar, also disturbs the inner ear of her opponents, inhuman agility.
    • Crusader - creates tens of “ghosts” which can fly and pass through non-living matter making armor useless against their spears.
    • Fenja and Menja - twins, women that can increase their size and become proportionally stronger and tougher.
    • Viktor - can steal and retain skills, is an actual master of a lot of things.
    • Othala - can give other people (both capes and normies) a minor power for a couple of minutes, (probably incomplete) list of powers are - more or less complete invulnerability, super-strength, super-speed and most importantly - regeneration, E88 have their own healer.
    • Alabaster - every ~4 seconds his body completely resets to an undamaged state, otherwise normal human. Except that he’s an albino, so very white, not sure if power-related.
    • Krieg - manipulates kinetic energy in a radius around him, basically slowing down any attacks and people, while he’s moving unopposed.
    • Rune - also jokingly called “Sabrina the Teenage Nazi” in the fandom - the only teenager in the group, if she touches an object she can telekinetically manipulate it later. Usually moves people around by flying on a huge chunk of concrete.
    • Night - completely brainwashed robot-like person from Europe, when nobody sees her she automatically transforms into a powerful monster that nobody knows how it looks. Also the transformation fully heals her (maybe fanon? idk).
    • Fog - completely brainwashed robot-like person from Europe, he can transform into a cloud of caustic fog. Insane combo with Night, they are “married”.
  • ABB (Azn Bad Boyz)
    All of the asian gangs joined by the iron fist of Lung.
    Members:
    • Lung - incredibly powerful, he gets bigger and stronger as the fight progresses, his regen speed increases too. If the fight is long enough actually turns into a huge dragon-like creature. Powerful regen and pyrokinesis.
      Fought Leviathan in Japan for hours “to a standstill” - but really Leviathan just left, after the entire island of Kyushu was sunk (11% of entirety of Japan) - which was one of the biggest endbringer losses and the reason there are a lot of asian immigrants everywhere.
    • Oni Lee - doesn’t really have any will of his own, just follows Lungs orders, doesn’t feel anything when killing. His power is line-of-sight teleportation, but he leaves an independent duplicate behind for a few seconds (that later dissolves into ash). Loves grenades, because with his powers they are literally infinite.
    • Bakuda - very recently acquired by Lung (after the start of the story?.). A bomb Tinker - also a complete idiotic maniac. Her bombs have a shit ton of exotic power-like effects, she likes to implant them into people, has a dead-man switch to explode everything she ever made when she dies. Insane synergy with Oni Lee, as he is able to copy her bombs.
  • Merchants (or Archers Bridge Merchants)
    A large but not very organized group of drug users, makers and sellers.
    Members:
    • Skidmark - the leader, can create and layer kinetic fields, kind of like Portal blue gel?. but they can also float. Those fields accelerate objects passing through them.
    • Squealer - a vehicle tinker, usually makes Mad Max-esque monstrosities. Notoriously has a stealth field technology that she uses on her things.
    • Mush - can gather trash around himself into a sort of trash armor/golem/mech, a few stories high.

Boy am I out of wind, and that’s only like half at best. Will probably add more here
Described most of the characters you can expect to encounter at the start of a Worm story, mostly without spoilers.