Ned has masochistic tendencies always throwing himself into new challenges in order to expand his abilities. He could keep his temper for a long time until he didn't, then he became entirely destructive. Ned revels in his role as a monster and takes pleasure in expanding his abilities and taunting his victims.This had given him a dangerous reputation.
Nothing pleases Ned more than being given a chance to get hurt, to the point that he secretly wishes that Siberian would try to seriously hurt him. This tendency has been used against him numerous times.
Originally Ned was a feeble narrow shouldered man, only five and a half feet tall. Based on his clones after Ned gained his power he grew taller and his form broadened, his face twisting and gaining his first venom sacs, with his arms segmenting.
By the time of the Slaughterhouse 9 visit to Brockton Bay Crawler resembles a black six legged dinosaur-like beast the size of a van, bursting with raw strength while also mobile enough to tear into prey or evade high speed projectiles. His entire body is covered in scales, spines, and bristling hair where thick armor plating doesn't protect vital areas. His mouth is large and fish-like, filled with mis-sorted fangs; his saliva is highly acidic. Eyes and eye spots run along the entire length of his body. From the knees of his foremost pair of legs, 3 smaller pairs of limbs resembling human arms emerge.
He was still verbally communicative but his voice had become a low grumble, barely recognizable as human anymore. 
Crawler's power was adaptive regeneration. Any injury he suffered would heal with ridiculous rapidity, usually in a way that made the healed area resistant or immune to the source of the injury.
He had a "core", whose destruction was the only way to ensure his death. It was not located at his brain, but rather closer to his center. Destroying his brain could slow him down, but it would not kill him.
His regeneration from damage is measured in seconds, replacing his nervous system, then his skeleton structure, and then the soft tissues.
His regeneration was able to reject Flechette's bolts bonding to him at a molecular level.
This adaptive regeneration had eventually turned his body into a monstrous form. This was due to his adaptations providing ways to defend himself better, not merely passive defenses. His modified limbs mean this his dexterity hasn't suffered for his growth and can even be rearranged to enhance his agility on different terrains.
By the time the Nine became active in Brockton Bay he was able to take the heat of a small nuke and could walk through burning buildings lit by White Phosphorous unscathed. Sundancer's abilities may have had a minor impact but Crawler would only have adapted to it. His internal organs had also been rearranged and reinforced, with several redundancies, creating an incredibly advanced and resilient organic system. These include his vision from the hundreds of eyes and an enhanced sense of smell used for tracking. However, some mind-affecting powers do affect him.
Crawler had an unbelievably strong caustic spit that he could launch at targets.Panacea, struggling to make a counter, described it as consisting of self-replicating enzymes that consumed the target, floating in a strong acid.
He never had the same powers for long given his constant adaption. However, his power could potentially have forced him into an immobile shape, allowing him to be buried. When exposed to Armsmaster's nano-thorns, body parts that were disintegrated turned into organic nano-thorns themselves.
Crawler came to Brockton Bay with the rest of the Slaughterhouse Nine. His choice was the buried girl, as Cherish had termed her. He was unable to attack her, given the very thick metal doors, and eventually left her and her host's people be.
Later participated in the massacre of the Merchants, where he met Scrub. It was here that the new testing regime was agreed upon.
Crawler was relaxing in a abandoned apartment when an un-smelled trespasser entered and tried to kill Bonesaw.
He was with the Nine when they were ambushed by the combined team of Travelers and Undersiders. The attackers captured Shatterbird and Cherish, though the Nine were able to capture Grue. Trickster was able to cause him some inconvenience.
The next day he was back trying to fight local parahumans.
Skitter used silk to bind up him up, temporarily immobilizing him.
Later during some actual fighting he attacked a protectorate team with Mannequin. When the team retreated Crawler was able to win against Weld without assistance.
Crawler was finally killed through having his entire body turned to silicon by salvaged tinker explosives used in a bombing run ordered by Director Piggot. Piggott convinced Crawler to subject himself to the blasts by telling him - through Weld - that the bombs would be able to hurt him. He was killed by that bombing run, along with Mannequin.
In an early draft of Worm, back when it was called Guts and Glory, Crawler was named "Troll". The ability of Trolls in Dungeons & Dragons to recover from any injury is a piece of information of indeterminable importance.
The constant need to conceal the recognizable Crawler may be the reason that the Slaughterhouse Nine were so hard to track as they moved between cities
Was "unstoppable" in the words of Wildbow and included in the Nine due to the authors admitted predisposition of torturing his characters.
↑Crawler – Member of the Slaughterhouse Nine, Crawler is a monstrous figure who heals with incredible speed and adapts natural defenses or augmentations in response to any healing. - Cast (spoiler free)
↑ 2.02.12.2Crawler, he knew, wouldn’t show any signs of boredom or restlessness. When he lost patience with things, it was an explosive affair, almost unmanageable. [...] Crawler wanted to be stronger, and remained with the group because it put him in constant danger. His other motivation was more subtle. He was patiently awaiting the day Siberian might honestly and brutally attempt to take him apart. The only stick Jack could wield was the possibility that the group might dissolve before that happened. On the other side of the coin, the day Crawler decided there was no longer any threat that could evolve him further would be… troubling. It was why Jack had ordered Siberian to let the boy with the glowing hair go. Finding the lad again would give Crawler something to do, and it would give Crawler a taste for what Siberian had to [...] The buried girl was only a candidate because Crawler hoped she was strong enough to fight him. Either she would fail to hurt him and he would grow tired of her, or she would succeed and he would have no reason to stay in the group. - Excerpt from Interlude 12
↑ 3.03.13.2“Run, little girl!” Crawler’s broken voice carried, a rumble so low I could feel it. “I’ll get free! I’ll catch you! I’ll hold you down and lick your skin until it melts! I’ll pluck your eyes out with the tip of my tongue! I have your scent and you cannot ever stop me! You cannot ever escape!” - Excerpt from Prey 14.4
↑“Crawler.” No portrait, this time. It was a still from a surveillance camera, a misshapen silhouette, not even humanoid, in a shadowy area. I’d come across stories about him when I’d been researching possible superhero names for myself. Not pretty. - Excerpt from Parasite 10.6
↑ 5.05.1“Crawler and Mannequin observed to be in the blast site.”
“How did they disengage while keeping them there? They- they did disengage?”
“Clockblocker managed to tether Mannequin in place. Crawler freed himself from the same trap by tearing himself in two against the immovable object. It was Piggot who managed to keep Crawler in the blast area.”
“She had Weld pass on a message, telling Crawler what we had planned. He was so tickled at the idea that we would be able to hurt him that he stayed where he was while the teams made their retreat.”
↑ 6.06.1Nearly three weeks of work down the drain.
Already, she was figuring out how to solve the problem. She’d have to stagger it, introduce memories in phases, starting with earliest and working her way forward. Maybe it would be easier, organized. She could consider each member of the Nine in turn and decide if they had been treated well as babies, if their home and school lives were comfortable… that would be a yes for someone like Mannequin, less so for Ned, for Crawler.
She typed on the computer for a minute. Special disposal procedures for Crawler. The rest could be boiled to death. - Excerpt from Interlude 25
↑The second Crawler was more careful, grabbing a hostage and making his way out the gap. He hadn’t transformed into his truly monstrous self. Bipedal, the size of a bodybuilder, his face no longer human. A long tongue extended out between rows of teeth, and his throat was swollen with an acid sac, as though he had a goiter. Eyes surrounded his face, which was already bearing the rigidity and light armor plating that would intensify with further regeneration.
His arms had already split into two limbs at the elbow, and each ended in claws. He used them for a grip on the metal to climb on the outside of the truck, penetrating metal with strong hands and sharp talons as he dragged his hostage along with him. He perched on the roof, holding the hostage over the disintegration field, staring at the second Azazel. - Excerpt from Interlude 26.x
↑I could sense Regent’s group, running to cover. Ballistic was bombarding Crawler, relying on the impacts to drive the brute back. Crawler was fast -and he was agile, with preternatural reflexes- but Ballistic was unloading on him with projectiles that moved faster than sound. Crawler dodged only two in three, and Ballistic followed up on any successful hits with a series of shots to pound Crawler into the nearest available surface and pin him there. Genesis had formed a body that was winged. It resembled a pterodactyl with arms, a griffon or something in that vein. She was making an effort to drop large chunks of rubble onto Crawler. He was strong enough that it barely slowed him down, but time he spent hauling a section of wall off of himself was time for Ballistic to get his hands on material for another shot. Shatterbird offered support with a constant hail of glass to harry Crawler and keep him from finding traction on the pavement. - Excerpt from Prey 14.4
↑Crawler, the most monstrous member of the group, loomed over the rest. His chest was ten feet deep from front to back, his head the size of a small car. He combined the most effective features of a bear and a panther. Sinuous, flexible, bristling with quiet menace, but also brawny with muscle. He had armor plates covering him, with scales where armor wouldn’t allow him optimum flexibility, and spines and coarse hair where the scales wouldn’t do. Head to toe, he had the coloring of an oil slick, black by default, but scintillating with rainbow hues in just the right light. A hundred black orbs studded the length of his body, set into the plates of armor. Caustic venom virtually poured from a mouth that bristled with mismatched fangs, spattering precipitously close to Cherish and eating at the concrete rooftop. Perhaps most unnerving of all were his six legs, each forking at the knee or elbow joint, with one larger limb ending in scimitar-like claws and a smaller set of limbs for each; tentacles for the rear four legs and a long fingered human’s hands for the forelimbs. - Excerpt from Interlude 12
↑ 10.010.1Shatterbird scowled. “Then who or what was that? Crawler, do you know?”
Aisha backed toward the front door. She stopped as Crawler appeared in the doorway that led from the kitchen to the front hall, looking through to see his teammates on the far end. His voice was a mangled mess of sounds that only barely approximated anything like speech. “I don’t smell anyone.” - Excerpt from Interlude 13.5 (Donation Bonus)
↑Ned Crawler Powerful regeneration and gains personal adaptations in response to any damage taken. Slaughterhouse 9 - ParahumanList, Bolded edit by Wildbow
↑I should rephrase: The source(s?) of energy that people are drawing from are kind of important & aren’t being ignored/handwaved. That said, some capes are pulling forth ridiculous amounts of energy/mass from nowhere and Crawler is among them. - Comment by Wildbow] on Interlude 12
↑Brutes (esp. regenerators) and changers often relocate their cores/coronas to the hardest to access part of their body, or adapt to do without. Crawler's wasn't in his brain, for example. - Reddit comment by Wildbow
↑ 14.014.1Crawler = Contessa can avoid harm/evade full grown Crawler until she gets her hands on a weapon/individual that can hurt him, target his core. Not-fully grown Crawler you can best by controlling the damage & resulting evolution to force him into an immobile shape. Bury him in concrete/sand/whatever. - Comment by Wildbow on Spacebattles
↑Brutes (esp. regenerators) and changers often relocate their cores/coronas to the hardest to access part of their body, or adapt to do without. Crawler's wasn't in his brain, for example. - Wildbow on Reddit
↑ 16.016.116.2Crawler was one of the two group members who had yet to rejoin the group. He was engaged with a young man with a glow that suffused his hair and emanated from his eyes and mouth. White flashes appeared with little accuracy and devastating effect, carving spherical chunks out of the brute. This only encouraged the monster, and Crawler eagerly paced closer, his wounds closing together with a startling rapidity. So few things could hurt Crawler these days that Jack rarely got to see the regeneration in full effect. Crawler’s healing powers appeared to play out in fast-forward when compared to even the regenerators who could heal wounds in seconds. Hundreds of pounds of flesh were replaced in one or two heartbeats.
One eruption of light hit Crawler in the dead center of his chest. It made him pause, no doubt removing one of his hearts and some of his spinal cord. The boy with the glowing hair pushed his power into overdrive, calling forth a series of flashes that exploded in close succession. One caught Crawler in the face, revealing only a cross-section of his head, complete with a bisected brain, a skull six inches thick and the interior of Crawler’s mouth. Crawler collapsed.
Crawler’s brain grew back to its full beach-ball size in one or two seconds, followed closely after by the healing of the skull, the reappearance of his facial muscles, then his skin, hair, spines, scale and armor plating, roughly in that order. He shook his head like a dog with water in its ears and looked around, searching for his quarry. - Excerpt from Interlude 12
↑Flechette fired a bolt straight into Crawler. It penetrated his face and stuck there. Little surprise on that front; I’d seen her stick Leviathan with one of those giant needles. Crawler’s face bubbled around the wound where it was rejecting the foreign object. Almost imperceptibly, it began to slide out.
He rumbled with a low, guttural laugh, mocking. Was he enjoying himself? He was a masochist, and it was the rare thing that could hurt him. - Excerpt from Prey 14.6
Crawler–How does his regeneration “work” if, say, he is cut in half? Which half regenerates? Does he have a “core” like Echidna’s, or does one of his organs function as such? If so, what happens when his Core/brain/heart/spleen is cut in half or destroyed?
Crawler – Q1A1. His form is monstrous because the adaptations aren’t purely defensive. His power provides the ability to defend himself better. Multiple legs to give him more stability so he can’t be knocked over, etc. - Comment byWildbow on Extinction 27.4
↑Crawler had reached Grue and was scaling the side of the building with surprising speed. I’d taken him for a quadruped, but apparently his joints were modular. His proportions were more simian, now, and he was climbing up the side of the building twice as fast as I could have run it if it were laid out horizontally. - Excerpt from Snare 13.6
↑He can be killed if annihilated, but by the time he shows up in story, he's been at it for a few years, hanging with a pretty nasty group calling themselves the Slaughterhouse Nine. You basically need to dig into the unconventional weapons (ie. stuff made by tinkers; stuff-makers like Iron Man) or very specific powers that can work around armor that can take a small nuke. - Reddit comment by Wildbow
Piggot spoke, “Legend, Ursa Aurora, Prism, Weld, Assault and Battery will occupy him until we can contain him. He’s still vulnerable to physics. I’m hoping the white phosphorous explosive will keep him in the area long enough for us to put measures in place [...] The plane wasn’t as fast as I’d thought it would be. It appeared from the clouds and crossed the skyline a distance away, at an altitude not much higher than me. It left a muted roar in its wake, and the payload of bombs. Black specks, smaller than I would have guessed, but more numerous. Fifty? A hundred? I couldn’t tell from my vantage point, and I doubted I could have made an accurate estimate.
The bombs were targeted at the parking lot where Jack and Bonesaw had been. They detonated across the surrounding neighborhood, a carpet of explosions and flame that ripped through everything. In a heartbeat, an area that had been drowning in stagnant water was lit up by fires that rose higher than the smallest buildings. [...] “Crawler’s probably taken worse. I can picture him crawling into an incinerator and sitting in there for long enough that he can take this.” [...] Crawler- I could see him prowling the streets, soaking up the flame without a care. He was headed in the general direction of the parking lot where the heroes were, taking his time, his movements languid. - Excerpt from Prey 14.5
↑We reached the scene of the ongoing fight with Crawler. Sundancer was off the dog and on the ground the second we could see him, creating her orb and increasing its size. She was fireproof, but she didn’t have the ability to grant that benefit to others. Once she was standing, the orb was free to grow.
“Don’t use your orb on him,” Tattletale cautioned. “Won’t do us any favors, and it’ll only make him stronger for the future.” - Excerpt from Prey 14.5
↑Wildbow: Crawler's testicles? Wildbow: They'd be positioned like ovaries are. Wildbow: The dangly bits dangle because our body needs to contract/drop them to adjust their temperature. Wildbow: (This is also why they shrink in the cold) - Crawler's too advanced for that. - Comment by Wildbow on Spacebattles
↑Question by braincraft: What classification is used for enhanced or expanded senses? There are a lot of characters in Worm that have something along those lines, and outside of Worm there's stuff like Superman's telescopic vision, x-ray vision, and enhanced hearing, or Wolverine's ability to track by scent.
Answer by Wildbow: Thinker. In some rare cases they'd fall under a Brute classification. - RPG.net comment by Wildbow.
↑I had a single grenade, and I knew that wouldn’t even make Crawler flinch.
Crawler spat a caustic spray onto Cache and Clockblocker. I could see the mucus fizz and pop from my vantage point high above. [...] Maybe he’d anticipated that, but he couldn’t have anticipated the acid spittle. Holes began to appear in the fabric of his fireproof costume.
He managed to maintain his composure- I had no idea how. I couldn’t imagine how it must have felt to be down there, feeling the heat and smoke coming in through the widening holes in the fabric. He began using his power, calling up the shadowy geometry that would deposit the heroes onto the battlefield. [...] I was so busy tracking Mannequin, looking for an opportunity to shoot him again, that I nearly missed what happened next.
Crawler got close enough for Glory Girl to swing a punch. She took the bait and swung, then twisted in mid-air to deliver a kick. He pulled just out of reach of both hits, then opened his mouth to retch spittle and bile all over her.
It had the same effect on her costume that it did on Cache, only far, far faster. In moments, she was down to the skin-tight costume she wore beneath her white and gold dress, her forcefield protecting her.
I pulled a grenade free. Maybe it could distract him long enough for her to-
Crawler surged forward, slamming his head into her. Like a spiked volleyball, she slammed hard into the ground.
I could see her skin turning red, then black, where the spittle had covered it. Flesh melted away to reveal muscle, then the acidic vomit began to eat away at that. She screamed, frantic, thrashing, oblivious to the flaming patches of ground that she was rolling into. - Excerpt from Prey 14.5
↑“I can’t- can’t figure out what this venom is. I can’t touch it to see if it’s organic, um, I can only see what it’s doing. At least part of it is enzymes. It’s denaturing proteins in her cells and using the byproducts to build more enzymes, and it’s breaking down lipids as a side effect, shit. Oh god, and there’s more to it. The fluid the enzymes are swimming in is some kind of acid.”
“Can you fix her?” Tattletale asked.
“So much to do,” Amy mumbled, “Have to counter the acid with some kind of physiological byproduct, have to stop the enzymes from liquefying her entire body, and repair the damage. Trying to make some kind of firebreak to stop the spread of the venom, withdraw the proteins the venom is using to propagate itself. There isn’t enough tissue in her body for everything I need to do to fix her.” - Excerpt from Prey 14.6
↑He was struck by the Azazel that still approached, caught by a long tail and flung down at the ground. He rolled, and in doing so, he rolled into the same nano-thorn rails that had taken down his brother. Half of his body was disintegrated in an instant.
It regenerated swiftly as he scrambled away on his three remaining limbs. This time, as the flesh swelled out and took form, there was a blur around his right arm, red, more at his shoulder, along his leg.
The Azazel struck out with a tail, and he blocked the blow with the newly grown arm. The tail sheared off as it made contact with his newly grown defenses. The chunk of metal rolled into one of the cars further down the road. Still, Crawler stumbled from the force of the attack. To avoid being disintegrated, he drew his freshly altered arm back towards the barrier behind him. Where his blur met the blur that extended from the rail, the two nano-growths merely pressed against one another, almost springy, neither severing the other.
He reached back with his unaffected arms and intentionally disintegrated them. They regrew, with alterations matching the ones he’d grown on the other side of the body. Better equipped, he stalked towards the Azazel that had laid down the rails, his back to the one that had struck him from the roof of the bus. - Excerpt from Interlude 26.x
↑Crawler threw himself into the point where the crowd was thickest. Bodies flew as he moved on his two rearmost legs and swept the other four claws and two tentacles through the ranks of the Merchants. When everyone within his broad reach was dead or suffocating from the paralytic venom, he turned toward the wrecked aircraft and began advancing with a more measured pace. Each of the hundred eyes along the length of his body blinked to clear away the blood and dust that had spattered him in his all-too-brief spree.Jack watched as someone drew a gun and pointed it at Crawler, then reconsidered. - Excerpt from Interlude 12
↑Crawler’s pause to grab concrete had bought me time to get my bugs into position. They swept over Crawler, laying down braided ropes of silk joined by adhesive lines and thin gossamer. Even caterpillars began offering their assistance, using the silk they produced for cocoons.
He was a big guy, but it was a lot of silk.
I could see how it hampered his movements. There was even something approximating surprise on his face as he dropped down so all six legs were firmly on the ground, and his forelimbs didn’t extend as far as he’d expected. He tried to run and found himself hampered further.
Crawler sported two or three tons of physical prowess, and his power had fine tuned him into a physical specimen like few others. My bugs had millions of years of evolution to refine the quality of their silk and their ability to produce it.
↑“I wouldn’t say that, Chevalier,” Jack responded, his voice carrying through the vast chamber with two or three hundred vats spaced evenly throughout. “See, we mixed things up a little. There’s a specialized cleanup area that can kill the Crawler clones. We gave them their powers right off the bat. Mixed them in with the others. You’ll have to be fairly discerning, and devote manpower to the task.”
I thought about using my power, but there weren’t any bugs native to this area. I was limited to the ones that I’d brought with me. Not enough to cart two or three hundred children off to some special device.
“A distraction,” Defiant said. “There’s another option. A bomb. If we track down the device Dodge used to create and maintain this dimension, we can collapse it.”
“How fast?” Chevalier asked.
“Fast,” Defiant answered.
“Poor sportsmanship,” Jack rebuked them. “Let’s try a different distraction then.” - Excerpt from Sting 26.6
↑“You will help,” Defiant said. “After. When you work, it’s going to be with supervision. Panacea can check your work and vice-versa.”
Bonesaw sighed. “My lab. The alternate dimension, the cloning vats-”
↑The first iteration of the Nine, back when I was writing a story with Glory Girl and Panacea as protagonists, the members included many of the same people. Crawler (then named ‘Troll’), Shatterbird (‘Breaker’), Bonesaw (The Maiden) and some who aren’t in this iteration. - Comment by Wildbow on Interlude 13.5 (Donation Bonus)
↑1114: [...]Why oh why author did you give creepy evil mass murderer psychopaths TWO unstoppable guys? [...] Wildbow:Why did I give them two unstoppable guys?
I’m a sadist. I admit it. I’ve got a bit of a streak of schadenfreude in me. I enjoy being mean to my characters.
But I’m also glad when they rise above whatever I’ve decided to inflict on them, so it tends to balance out, thankfully. - conversation in Interlude 12