"I won't spoil the conclusion if you're eager to see this through."
This article contains MAJOR SPOILERS relating to
some of the most pivotal parts of Worm. Although all articles may contain spoilers, this article will reveal major plot twists and should almost certainly be avoided unless you have finished the story.
"I'm guessing there's more that I don't know about?"
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Shards, also known as faeries, passengers or agents, are fragments of incomprehensibly immense colony organisms that serve as the source of parahuman powers.
Shards resemble crystalline structures folding and unfolding like hypercubes.
Each Entity is comprised of "trillions upon trillions upon trillions" of Shards. When two entities collide, rubbing against each other, their Shards can be damaged or destroyed by the friction and pressure, but they are exchanged between the two. Before coming to Earth, Eden and Scion cast off the vast majority of their Shards.
They travel along predetermined paths after being cast off by an Entity in space, "raining down" on the Earths over the course of decades. Once they landed, Shards resided in other worlds, uninhabited worlds, and they remained cloaked and concealed in areas humans were unlikely to explore. 
"All of our powers stem from the same source. It’s this big alien bastard that we keep seeing when we have our trigger events. Except each of his cells is coded with just a fragment of his brain and a technique he uses to manipulate his environment, protect himself or attack others. He spread powers around Earth as part of a way to stress test them. He wants to leverage our brains and imagination to figure out ways to make the most of these abilities or innovate new ones."
A dead shard is not connected to the larger shard network and by extension the entities. Many dead Shards were also damaged.
The large numbers of Eden's Shards were damaged, corrupt, or dead. This meant there were more parahumans than the entities had intended, rendering them useless to the cycle. Vikare's Shard was such an example, though it was still able to grow properly as long as he was alive.
Scion would generally destroy them on sight as he saw them falling.
Some Shards were vital to an Entity, and not intended to be given out. If their vital processes were separated, they could die. Scion saw some of Eden's vital Shards seemingly falling and being sent to hosts after she crashed.
Sometimes, a Shard begins splitting off, ready to find a (generally young) host similar to the original target and attach to them with the benefit of more experience. This generally takes time and/or stress on the part of the host. It is possible for a single shard to fragment until it grants a wide variety of powers to an entire planet. It's possible for a Shard to bud before or at the same time as a trigger event.
Very rarely, the host will experience a second trigger very similar to their first trigger, causing the bud to consolidate in the current host instead.
Although the entities consider the different "fragments" to be separate shards, and the buds require their hosts to remain in close proximity if they want to communicate, on a physical level the shard is simply devoting a part of its "CPU" to the new host. This is because the main portion of a shard is largely inactive, with the "active" portion being that attatched to the host.
When Shards bud or cross-bud there can be interaction between the parent Shards creating interesting effects. For example Golem's power derives partially from his Shards relation to Kaiser's and Allfather's, the manifestation of his power as limbs and similar derives from his mother Heith however.
Powers from multitriggers are from a mix of Shards. The Shards give up a small to moderate portion of themselves, and then leave the rest of themselves to develop normally while taking in info from multiple sources. The Shard will usually connect another, primary host as well, possibly with some relation to one of the grab-bag capes. This is primarily intended for the end of the cycle, and serves to stress-test powers and compare and contrast the smaller powers.
Ever since they first evolved on their home world, Entities have been composed of "clusters" of Shards, each with different functions.
Different Shards tend have different abilities, even if the powers they grant humans appear similar. Generally they are not supposed to give a specific power; different hosts and trigger events produce different powers. Since it furthers the main purpose of Cycles, which is recombination and search for possible applications of specific shards.
Although there are some specific "general"-shards, which will react to any potential Trigger event situation. Commonly a shard will only make a connection under a specific type of trigger event, that synchronize with their specialization. For instance, "Administrator" shard will always grant it's host some form of Master power. They will also skip a potential host if there is a better potential for their target trigger situation to happen in another related individual.
Every parahuman receives only a small portion of the potential abilities of their Shard. For example, a Shard may choose to apply it's powers to only one type of target; insects, humans, trees, etc.
Shards also limit themselves to avoid damaging the host. "Thinker Headaches" are one example of this.
The effects that Shards have on their hosts are dependent on several factors, including but not limited to: age of the host, the host's personality, the host's trigger event, how much the host embraces the Shard's need for conflict, and the nature of the Shard itself.
Generally the younger a person is the more heavily their personality is influenced by their Shard. The connection becomes "broader", removing or exaggerating almost every element of their personality. This does not necessarily mean that they are more powerful.
Some parahumans have particularly deep connections with their Shard when their personality is naturally in alignment with the Shard's desire for conflict. The Shard does not influence the person's personality as heavily, but the line between the two nonetheless becomes blurred.
Parahumans with very little connection to their Shard generally find that either they have "episodes" where the Shard takes over, or their power systematically acts according to the Shard's desires rather than the host. Examples of this include Garotte, Echidna and Leet.
Bonesaw speculated that she and Jack Slash both had deep connections with their Shards. The Fallen are generally very good at feeling the connection with their Shards.
Shards draw on a number of different factors to identify their host, including DNA, electromagnetic patterns, and traits humans don't have names for.
Individuals with the same DNA as a parahuman, even a deceased one, would possess a Corona Pollentia right from the outset. They still required a trigger event to gain powers, but it was extremely easy.
↑Link two shards together for cross-purposes, to augment one power (ie. means of increasing range or penetration of organic matter added to a shard with blaster/striker type power) or to add another power to the package (ie. Tecton's structural awareness added to the tinker shard), and you get... a shard. Each shard is a collection of data and mechanisms, and each 'shard' as we think of it is already composed of multiple shards. - Wildbow on SpaceBattles
↑They can alter the shards they put out there, before the shards hae mature, because a connection is maintained. No connection = 'dead' shard. - Part of a Comment by Wildbow on spacebattles
↑dead damaged shards are disconnected from the greater entity network that allows living shards like Zion's to function. - Comment by wildbow on Reddit
↑Some shards are damaged. Or 'dead'. Which isn't saying he's Cauldron.
↑Generally the trigger cause fits in the same general category. Brian had his second trigger for much the same reason he had his first. They can differ in nature. What's happening is that the entity is drawing from context and exploring/conceptualizing new uses for the powers (which are still in the metaphorical computer's memory, but not in the hardware that burned out in the trigger process). The entity begins splitting off, ready to find a generally young & similar host to target (piggybacking off the parent's context & experience for an easier triggering process/analysis) but then a major event prompts it to catalyze and consolidate in the current host instead. If it's in an adult before finding its way to the child, it can begin this splitting-off process (generally requiring time or a degree of stress to allow for the maturation). They are exceedingly rare (two noted in-story. Taylor didn't second-trigger in the last arc, to be clear), and generally speaking they do more harm than good. If it's a straight power-up, you're probably doing it wrong. - Wildbow on SpaceBattles
↑The one that occupies the structure has bred, now, fragmented into clusters of shards that could occupy others. Some shards have different focuses. This is the experiment, the test.
The fragments continue to divide, feasting on abundant resources, on light and radiation and the alien food sources it has started to learn how to consume. It spreads quickly now, across every possible variation of this world that sustains life.
The shards might seek out different hosts, if others are in range, as the perception-altering one did. They will fragment and transmit to other hosts, as they grow and develop. - excerpt from Interlude 26
↑Q: Do Brandish and Lady Photon have closely related or bud shards? A: Yes. Bud shards. One had it, then the stress they were under prompted it to bud, it found the nearby host who met the prerequisites. - Wildbow on SpaceBattles
↑ 11.011.1Some people have very little connection to their shards. Look at Leet - his shard actively sabotages him. Look at Echidna, or Sveta. You end up with disconnects, and stuff starts to stand out as the shard's behavior becomes more distinct, either in 'episodes' or a pattern of the power not cooperating. - Worm Web Serial Discussion III : After the End (Wildbow, SpaceBattles.com, 2014-01-15)
↑All around the entity, there were shards in varying states of maturation. The female’s was among the most mature. Seasoned by conflict, heavy with information, lessons learned, tactics, applications, organization. It had already fragmented once, heavy enough with information that it could afford to handle other roles. The fragment would have a derivative ability, and given proximity, it would hopefully remain close enough to exchange information with the shard that it had split off from. There were no signs of that exchange. The female had separated ways from the fragment. - excerpt from Interlude 26
↑More like the shard is just a big chunk of entity, somewhere between a crystal and a braincomputer, and it's constantly adapting and shifting gears to take in the data that the host is granting. When that starts slowing down, because the shard has seen enough permutations, then it devotes a chunk of itself to the processing for a new host (or to the existing host again), extending a tendril across realities. - Wildbow on Spacebattles
↑Kyakan: Back in Scion's interlude, he mentioned that Taylor's shard had fragmented, and was no longer in contact with said fragment (Aidan) due to having moved apart. However, in a later WoG, you clarified that a shard budding is more like designating a different portion of the same shard than physically separating. My question is why Taylor's shard would no longer be communicating with Aidan's, since they're physically re same shard? Am I misinterpreting the WoG?
Wildbow: @ Kya - Shards burn off a lot of their extraneous functioning when they manifest in a host. It gets a bit hard to word because the CPU is still in another dimension and is doing stuff, but the active part is mostly in the host. Scion is distinguishing the active portions of Taylor & Aidan. Kiiind of like how when you're talking to someone about stuff going on with your computer, you might gesture at the monitor, keyboard, mouse setup and not the desktop sitting on the ground to one side. - Wildbow on Discord
↑ 15.015.1*The progression of Allfather -> Kaiser -> Golem is largely informed and inspired by interactions with other shards. Golem from his mother, namely. This isn't a 'progression'. Just the shard reaching further afield. It could just have easily backtracked from Blade projectiles -> Blades from surfaces -> Blade Projectiles, given the right inspiration. - Second Gen Capes, Buds, Pings, and Second Triggers (Wildbow, Reddit.com, 2016)
↑1.) Powers from multitriggers are from a mix of shards. The shards, instead of going all-in, give up a small to moderate portion of themselves, and then leave the rest of themselves to develop normally while taking in info from multiple sources, just like a shard would naturally gather info and eventually reach the point where it could bud. Except in this case, the shard will usually just go find another host, maybe with relation to one of the multi's, maybe not, and empower them.
2.) There would need to be some common ground. It's very possible that, in a car accident where two individuals triggered, that one would get seriously hurt and be anxious about 'oh fuck, my life is ruined, what do I do!?", While the other is like "Oh fuck! I'm going to jail!" while being a little bruised. The former gets a major brute power with minor thinker, while the latter gets a minor brute power with a major thinker. And the shards want to keep them involved and interacting, so in pretty short order they start to really hate or really like each other. - Comment on Reddit
↑Multiple triggers are actually the endgame of the cycle, prior to the reabsorption and collapse. When virtually all individuals in the setting are parahumans, connected to shards, the introduction of multiple-triggers serves to stress-test powers and compare and contrast the smaller powers. - Weaver Dice Rulebook
↑Q: Are shards generally more likely to use more similar or more different mechanisms? For example, are two electricity controlling capes usually using the same method to control electricity, or different methods? Is someone like Panacea using a kind of precise telekinesis that could be used more generally and is used more generally in other shards, or is her shard using mechanisms that specifically work on biological materials? A: Depends on the shards. Generally different. - Wildbow on SpaceBattles
↑If a shard can give any power classification, depending on the trigger, Wildbow:For the record, some shards can, but not all. Some shards are almost always going to just trigger Master, for example, and you just won't trigger unless you're in a state of mind that lends itself into a frequency match for the scan-manton snap (as Bonesaw describes in 11.h). - Alternative powers.Wildbow, Reddit.com, 2017-06-??
↑In devising the actual trigger, we actually figure this out in a way like we would a Cauldron vial. We know what the shard does, and the key thing to figure out is how that shard expresses its power and how it manifests. The QA shard specializes in coordinating control over large numbers of smaller lifeforms. We see it in Skitter (bugs), we see it in Aiden (birds) and we see it in Chitter (rats). - What if Danny Triggered
↑In all three cases, he's liable to self destruct. The shard recognizes this, accepts it (in a way, the shard was sent to him by the entity for this reason), but then hops to a more viable host with a longer lifespan and more complex emotion. - What if Danny Triggered
↑ 23.023.123.2When we get our powers, the passenger manages this sort of scan, trying to figure out a way to apply a part of itself. So Taylor gets a power that's restricted to bugs, Canary gets a power that's limited to people. At the same time, the passenger kind of figures out if there's any danger of the power harming us, physically or mentally, and it sets down safeguards and limits. Headaches like Dinah or I get are part of that. [...] Every power has secondary uses, uses that are locked away. - Excerpt form Cockroaches 28.4
↑ Shards only very rarely 'make' people do anything. They pick their hosts with care, those people who are going to be inclined to use powers more or throw themselves into a given type of situation, they may nudge, or encourage more subtly, reinforcing behaviors they want with more power, more focus and utility in the power, or in damping down any drawbacks. In some cases, they may ebb and flow in terms of effectiveness, and in cases like Canary's, may ebb more for a long time, getting her to let her guard down, before a 'kill all the Japanese' chance comes up. - [Spoilers All Did Canary's shard...?] Wildbow, Reddit.com, 2016
↑The broadcaster had finished speaking just a moment before the craft had launched, oblivious to the blaring noise that had been intended to drown him out. What I don’t understand, is why a blank slate like you would default to doing good deeds, rescuing cats from trees. Why not turn to that violence, as our ancestors did? It drove them, just like it drives the basest and most monstrous of our kind.
Had he known he had a listening ear? Had it merely been a struggle to continue doing what he’d instinctively done for decades?
↑ijp92: so I guess you could say that no matter how much of an effect a shard/passenger/agent has on the personality/development of its host, its host will definately[sic] have a similar and likely far greater affect on the "personality/development"of the shard/passenger/agent.
↑“You want to see the faerie rise again, apparently, and Scion’s a big part of that whole equation.”
“Yes. I’m seeing what you’re getting at, Administrator. A conflict of interest?”
“We all have our parts to play.”
“Yes. Like actors taking a role in a play. We wear our human faces and harbor our dramas and fantasies, but it’s the same individuals playing the parts, as the play starts anew on a different stage, with different faces and forms. If it all goes well, a figure from the crowd joins the stage for the plays that follow, and the roles are refined.”
“And us… Queens and Kings. Do we have a bigger part? Leading roles?”
“Everyone’s the lead in their own story, Administrator. Some roles are bigger, some smaller, but none are more important, understand?” - Excerpt from Extinction 27.4
↑Bonesaw smiled, “And I know the secrets. I know where powers come from. I know how they work. I know how your power works. You have to understand, people like you and me? Who got our powers in moments of critical stress? The powers aren’t meant for us. They’re accidents. We’re accidents. And I think you could see it if you were touching someone when they had their trigger event.”
“I don’t understand.”
“You don’t have to. What you need to know is that the subjects of our power, the stuff it can work on, like people? Like the fish lady in Asia? The boy who can talk to computers? Our powers weren’t created to work with those things. With people or fish or computers. It’s not intentional. It happens because the powers connect to us in the moments we have our trigger events, decrypt our brains and search for something in the world that they can connect to, that loosely correlate with how the powers were originally supposed to work. In those one to eight seconds it takes our powers to work, our power goes into overdrive, it picks up all the necessary details about those things, like people or fish or computers, sometimes reaching across the whole world to do it. Then it starts condensing down until there’s a powerset, stripping away everything it doesn’t need to make that power work.”
“And then, before it can destroy us, before we can hurt ourselves with our own power, before that spark of potential burns out, it changes gears. It figures out how to function with us. It protects us from all the ways our power might hurt us, that we can anticipate, because there’s no point if it kills us. It connects with our emotional state at the time the powers came together, because that’s the context it builds everything else in. It’s so amazingly complicated and beautiful.”
Bonesaw looked down at Amy. “Your inability to affect brains? It’s one of those protections. A mental block. I can help you break it.”
“I don’t want to break it,” Amy said, her voice hushed.
“Ahhh. Well, that just makes me more excited to see how you react when you do. See, all we have to do is get you to that point of peak stress. Your power will be stronger, and you’ll be able to push past that mental block. Probably.” - Excerpt from Interlude 11h
↑Depends on the shard. Bonesaw elaborates on the idea by noting 'breadth and depth' in her interlude. If the shard gets you while you're young, it can shape your personality across the board, on a deeper level. The more conflict you're involved in, the more toeholds it gets to rewrite your consciousness and your subconscious. To alter your thinking, it needs to do it as a part of the trigger event, or as part of the brain's development.
In the extreme cases, the shard can leave you with an impulse (Must fight when a fight presents itself), help set up an obsession ("Wall myself in!"), steer a neurosis in one particular direction (specific hallucinations rather than random ones, of you hurting people, pushing someone down the stairs, etc), create a link between A and B (Being around fire makes subject lose empathy and inhibitions. With lower empathy and inhibitions, subject uses power to make more fire.), or steer a personality trait to an extreme (Must be on top, I answer to no one!), or they just overwrite stuff (Can't understand humans, only dogs).
In the lesser cases, it can be a nudge, hard to distinguish from one's own psychology. You might be on the fence about something, trying to make a call, and the passenger pushes you one way over the other, based on your own feelings of doubt or fear. It might tap into emotions, and dampen X emotion while promoting Y, just dampen them across the board, or take the joy out of day to day living while adding excitement to the cape life. A vague sort of depression that only goes away when one's out and fighting. Sometimes, as mentioned before, it's set up as a trap, a flood of emotion or a set of mental switches that get thrown when a prerequisite is met - such as a cape just steering clear of all confrontations, except the shard set it up so they can't, and they have a sort of limit break/command cutting in that mandates them to fight in one way or another. Or it plays off a limit or a berserk button that already exists - Damsel can't spend too long being anything less than top dog or she gets restless, and if she goes too long despite that, then she has to act, she's acting without thinking about it. This takes time and effort for the passenger, and a host that doesn't demand that time and effort (by circumstance or intent) is going to develop a better connection with the power. This in turn is a reward of sorts. If Damsel did kill the local capes and assume control over the area, fighting off all comers, she'd find her facility and control with her power just ramped up like crazy.
It varies from cape to cape and shard to shard, and it varies depending on the host, the host's background and the host's personality.
Beyond that, other influences include the passenger playing fast and loose with the power itself, as it controls the metadata, which may be more visible if the subject breaks from their norm in terms of consciousness (gets a concussion, tranquilized), working off base instincts and impulses like 'stay camouflaged' (be a little more creepy and unsettling), intimidate/dominate (passenger works behind the scenes to make you look a little more dangerous as you mutate/grow/surround yourself in the aura of your power), etc, etc. In more pronounced cases, the power is just plain controlled by the passenger, not the host, and the passenger makes the seemingly random or uncontrolled aspects generate more conflict... pushing a power to kill rather than leave someone alive, or a thinker power turns up a vision of something the subject didn't want to see.
On the macro level, too, don't discount the fact that some shards (particularly powerful ones that warranted attention) are just sent to specific people, with the idea that it's a combination that's going to promote more conflict just by the sheer dynamic of it (Powerful person with a destructive power, a desperate person with a power with negative implications). - Comment by Wildbow on Spacebattles
↑Jack had a different kind of connection. A deep connection. He was in alignment with the particular nature of his passenger. The passengers naturally sought conflict, and Jack had fed that need from very early on, and he had sustained it for years. The line between the two was so thin as to be impossible to mark, but Jack's personality remained his own. Altered, but not subsumed. - Excerpt from Interlude 25
↑Similar to the Herren Clan, they're a group of families with some members having powers, largely based around the southern states. They figured out that people with powers tend to have kids with powers, and are making the most of it. This leads to families with strong threads of a particular power type running through them.
Coin toss as to whether a given member believes what the cult is saying or not, that humanity deserves to be wiped out, so-and-so deserved to die at the hands of Behemoth, or the world would be a paradise if the Simurgh were to achieve full influence, if we only let it. It's telling, perhaps, that they don't actively interfere when the Endbringers come rolling around, though they might celebrate from the sidelines and try to get media attention.
They're loosely based on the Westboro Baptist Church - they want attention and the Endbringers are a sore spot for the vast majority of people around the world, an easy target. Depending on the family and the area, the approach differs. One might commandeer a radio station and and spewing vitriol over the airwaves, praising the latest Endbringer attack for the casualties. Another might call in another family from another area, then use ten Fallen parahumans and X number of unpowered Fallen to raid a small town with two or so heroes (or bait out a hero with a minor ruckus and then ambush them) to kidnap the heroes and induct them into the family, so there's more powers running through the bloodline.
They're hard to stamp out, unpredictable, and tend to live on the fringes of society, where they're harder to track and heroes need to devote far more effort to squirreling them out. There's also a tendency to give more power to the lunatics and assholes, because it furthers their nebulous agendas. They want to be loathed. In a more abstract sense, shards love conflict, and the fallen are very good at feeding it, so the fallen get rewarded by the shards. Breadth and depth. - Comment by Wildbow on Spacebattles
↑ 33.033.1Various elements that were unique to every individual served as a signal that the passenger could reach out to in an attempt at reconnecting with a host. DNA, electromagnetic patterns, patterns she could barely measure with instruments, all contributed, none was absolute. Once the connection was established, powers were possible as well. A moment of trauma sped the process along considerably. Her initial assumption had been that coming to life would be enough for the clones.
The Corona Pollentia was developing as the originals did, drawing from DNA to form as a lobe in the brain, right from the outset. The dreams formed the connections between the corona and the clone. The bonds were forming too quickly and easily. - Excerpt from Interlude 25
↑The shard, being alive, reports back with Scion and the broader network, and then goes to find a new host. - Wildbow on Spacebattles
↑Was there any of the original personality in there? The memories of the person that was? If there were, then it implied something ugly. Glaistig Uaine collected passengers, tapped them for power, and if this thing had memories, then what did that suggest about the passengers? - Excerpt from Extinction 27.4