A cruel and manipulative man with a love of theatrics. Jacob had a playful demeanor even while he was committing small scale personal pain or when coordinating wide scale atrocities with the backing of the Slaughterhouse Nine.
Every move and action he made was calculated to afflict change on the world around him for
the worse. He expresses a love for affecting
"keystones" in his introductory chapter, that could change the world around themselves as well as though he was an individual butterfly effect which highlights his grandiose self perception.
Jacobs' primary ability extends the cutting edge of any handheld cutting weapon far further than its' physical dimensions, no known upper limit to distance.
Effects on weapons such as Armsmaster's Nano-thorn would not function, only the blade itself was projected. What he can actually do with the weapon is limited by the physical capabilities blade itself; for example, he needed an actual butcher's cleaver to sever limbs instead of a dagger.
Jack's secondary power grants him enhanced intuition regarding parahumans, as well as an ability to influence the emotions of anyone connected to a shard. This makes him a tougher challenge in a fight than his more obvious ability suggests and causes him to instinctively avoid situations that the Nine couldn't overcome.
This secondary ability is so subtle that Jack himself is unaware of it, but it is effective enough that the Nine have been perceived as a near invincible S class threat since he took control of them.
Bonesaw also modified members of the Nine with various "safeguards"; sheathing their vital organs and major arteries in a protective sub dermal mesh, further wire reinforcement was put into the skeleton to avoid broken bones, with special attention was paid to the organs and spine to keep them functioning. She also rendered her teammates resistant to her pathogens, and granting them artificial neurons which allowed them to make plans Cherish could not see, it is unknown if this could be adapted for other Master powers.
Jacob was a young trigger. His mentally unbalanced parents shut him inside a bomb shelter with a radio link to his father, who gaslit him by convincing him that a war was underway. He triggered upon exiting the shelter and seeing that the world was fine, and having his entire reality challenged.
At some point during or before 1987, Jack encountered King and joined the Slaughterhouse Nine. He felt great displeasure at King's interest in grooming him as a pet project or new "Gray Boy", conspired with Harbinger to kill him
Jacobs reasons were ego-driven, feeling like King saw him as a personal pet project instead of a man in his own right.
Harbingers' reasons to revolt are unknown, though they were personally strong enough to warrant a violent coup.
Afterwards Jacob renamed himself "Jack Slash" with the specific intention of sounding harmlessly simple and absurd.
Under Jack's leadership, the Nine become synonymous with terror and death, caring nothing for political power or money.
They seemed unstoppable, hitting towns throughout the United States seemingly at random and killing as many as they could before leaving. They notably avoided using bombs or more traditional methods of mass destruction, opting to kill personally using their powers.
The recruitment process became a trial in which each existing member of the Nine would torture and attempt to kill recruits and survival meant being accepted as a new member.
After being informed of the Nine's presence by Coil, Dinah Alcott made a prophecy that if Jack Slash was not killed before he left Brockton Bay he would set into motion the end of the world.
Jack tracks down Oni Lee and offers him a chance to join the Nine. After Jack determines that Lee is unworthy, the two fight, and Jack grievously injures Lee. He takes the wounded man to the Anders apartment and breaks in, dumping Lee in the bathtub and confronting Theo Anders. He tells Theo that he will kill him and Aster as soon as Purity returns home. During the subsequent conversation, Theo convinces Jack to spare them by promising that he will become a great hero and stop Jack. Purity then returns from grocery shopping and is about to attack Jack, but he tells her that her powers have been weakened by recent cloudy weather and overuse and that she has little chance of defeating him should they fight. She reluctantly allows him to leave with Oni Lee, whom he later gives to Bonesaw.
↑ 3.03.1A combination of what Jaki said (Imp gets nudged away by her shard, she gets a bad feeling as she prepares to attack, and if and when she does attack her attack is off-target, or she hesitates, creating a window), intuition on Jack's part (suspicion, a hyperawareness of odd details, the movement of air in the room, 'it's too quiet', etc., happening to move to another location just as Imp strikes out), and leverage of the broadcast... Crawler wakes to initial commotion, he uses his full senses with his shard happening to kick into full gear (a la Skitter and her varying range) and/or moves across room, forcing Imp to back up from Jack, Shatterbird lashes out in a blind attack that happens to connect.
On that last point, the Nine can be considered to be an [editing to add 'unconscious'] extension of Jack for all intents and purposes. To Imp, it's just a 'This feels like a bad idea, I'm going to do it anyway! Fuck, missed! Oh shit, ow! Well now I'm bleeding and, it's pretty damn serious. That must be why it felt like such a bad idea!'
Take note of Jack's discussion of keystones in his first appearance. He's getting help in identifying points to manipulate, and then those points are getting nudged further in the broadcast. Communication is a two-way street. - Coments by Wildbow, archived on Spacebattles
↑“Maybe he thought you’d respect him for it, sir? He was always good at reading people.” And making them do what he wanted. Even me.
“Is that so? I’d like to think I’m much the same. A people reader. But my interest is in the design of people. What makes them tick? What holds them together? All too often, it’s one little thing. In architecture they call it a keystone. The one stone that keeps the entire arch from collapsing. The weak point. And I’m very, very good at finding those weak points. Can you guess what I’m talking about here? Why I’m in this apartment?”
“And you say you’re nothing like your father. You’re sharp, little boy.” - Excerpt from Interlude 11b
↑Shatterbird, who had deigned to observe for the moment, hovering over the scene, was an individual who craved validation. She would be insulted to hear it spoken aloud, but she needed to be powerful in the eyes of others, civilian or teammate. She could tolerate much, but an insult or a joke at her expense could push her over the edge. As carrots went, a simple word of praise could satisfy her for a week, and an opportunity to shine could sate her for a month. It was why he allowed her to ‘sing’ each time they arrived somewhere new, even as he found it repetitive and boring, brooking the same scenarios time after time. Her stick was easy enough: the threat of physical harm, or the embarrassment of being made to lose control. Were she to attack a member of the group, Siberian or Crawler would retaliate, and they would hurt or kill her. It would be inevitable, unequivocal. The idea of the shame she’d feel in that ignoble defeat held her back as much as anything. - Excerpt from Interlude 12
↑“Jack Slash.” Jack looked like someone on the attractive side of average, his dark hair cut short and styled with gel. His beard and moustache were immaculately trimmed so that each had a serrated edge, and his shirt was wrinkled, only half buttoned so his hairless upper chest showed. He had kind of a Johnny Depp look to him, though he had more of a widow’s peak, a longer face and lighter eyes. Good looking, if you looked past the fact that he was a mass murderer. He held a small kitchen knife in the photo. - Excerpt from Parasite 10.6
↑Jack only smiled, his eyes crinkling a bit at the edges. He was getting older. It was reassuring and spooky at the same time. He’s the daddy of the group and I’m the kid and he’s getting older which makes him more daddylike.
But it meant he moved slower and got tired more easily. It was only a matter of time before he made a mistake, lost a fight. - Excerpt from Interlude 25
↑“You thought Jack had a thinker power. Why? What?”
There was a pause.
“Because he’s like Weaver. He reacts like someone that is way too aware of what’s going on.”
Acts like me?
I’d made the comparison myself, but I’d tempered that, held back as I formed that conclusion. Hearing it in such a blunt way stung as much as a slap in the face.
“And you sent in the D.T. guy because-”
“Because Weaver surrounds herself with bugs, and Jack surrounds himself with capes. The non-cape is the only variable we haven’t seriously tried. The competent non-cape.”
Tattletale nodded, “Thought so. So let’s think about that. He’s got a thinker power that lets him manipulate parahumans, or read them, or gauge how they’ll react. He uses it, probably unconsciously, to constantly maintain the edge. And he gets bored. You’ve seen him get bored, haven’t you, Riley?”
“Yes. And when he gets bored, he sets up scenarios like the game in Brockton Bay, the test with Golem coming after him, whatever else. It usually falls apart before it comes to a head, because Jack is chaos incarnate, people cheat, Jack cheats, and so it goes. So tell me, do you really think he wouldn’t let you have a little slack to see how you’d operate?”
Bonesaw didn’t respond.
“Yeah. Exactly,” Tattletale said. “Your art? It’s his art. Your power and everything you do with it, it’s stuff he’s shaped.”
“That’s not true. I come up with my own ideas,” Bonesaw sounded almost defiant. She’d also, I noted, forgotten the original message, saying her art wasn’t important to her.
“His ideas. Everything’s tainted with Jack. And you know it better than I do. You can think of all the little scenes and conversations. How your favorite projects were the ones your family applauded. The ones Jack praised, above all.” - Excerpt from Extinction 27.2
↑Jack's dynamic hinges on the fact that he surrounds himself with members of the S9, which are effectively a wrecking crew vs. the unpowered, he has a great deal of clout when it comes to raw intimidation, and his power makes it so that he generally triumphs over powered individuals where possible, and instinctively avoids situations where he can't avoid the ones he can't beat.
The situation as you portray it is essentially, "You have to capture Taylor, there are no bugs in the area, her friends aren't nearby and don't know her situation, and she's hogtied in the basement without any ability to undo the bonds herself." - partial comment on Reddit
↑“You’re not really in a position to be making demands,” Trickster said. “You’re bleeding to death, and we do have the ability to hurry the process along.”
Cherish shrugged. “Bonesaw gave me the works. Mesh sheaths for every major artery and organ, wire reinforcement for my skeleton. It’s not going to kill me anytime soon.”
I made a mental note of that. Chances were good that Jack, Bonesaw and the other more vulnerable members of the Nine had some similar protection. How differently would things have played out if Ballistic had used his power and blown them up?
“I could,” Trickster threatened. “Or we could wait and see which happens first: Either you agree to share the information we want or you slowly bleed out.”
“A game of chicken? I’m down.” Cherish prodded her injury with a fingertip. It was clear it hurt, but she still stuck a finger into the hole and investigated some. “The auto-injection pump is dosing me with painkillers and antibiotics now. First time feeling this stuff work.” - Excerpt from Snare 13.7
↑ 14.014.1“A benefit of little Bonesaw’s smoke,” Jack answered. “If I recall correctly, it’s something of a safeguard in case she accidentally deploys a concoction she hasn’t immunized herself or the rest of our team against. The fact that it works against bugs and small rodents is a side benefit, rather than the intent. Bonesaw’s work has made us members of the Nine more or less immune to disease anyways.”
“And the gunshot?”
“Subdermal mesh. There’s more protection around the spine and organs, and you landed that shot pretty close to my spine. It hurts quite a bit.” - Excerpt from Prey 14.10
↑Jack paced back and forth, two or three steps at a time, gesticulating with his knife. “I was looking forward to Cherish’s attempt. Bonesaw and I even had a plan in mind. I wanted to see what she did, how she worked around Siberian’s immunity to her power… then the safeguards Bonesaw implanted in us would have kicked in and released us from her thrall, and oh, the look on her face. To have seen that would have been so very worth all the trouble. And that girl just spoiled it all.”
Jack was getting heated, talking mostly to himself. “That was the whole point! To see how long we could go without tipping her off. Bonesaw helped with some surgery, even some artificial neural connections that Cherish wouldn’t be able to see. So much work and preparation ruined.” - Excerpt from Plague 12.4
↑Jacob was a young trigger. His parents were a little mentally unbalanced, and they shut him inside a bomb shelter with a radio link to his father, who wanted to use it to instill Jacob with sufficient fear of the threats of the outside world. A one-way communication, feeding into and playing off his fears, gaslighting, convincing him a war was underway, it broke the boy, but he wasn't released when he was broken. He stayed. His parents left him in there, mostly because it was easier. In a twisted way, having a boy in the shelter to hear dad's words, it made Jacob the exact son they wanted.
He triggered on exit, his entire reality challenged on seeing that the world was fine.
Feels awkward, written that way, rather than outlined in a proper interlude. Ah well. Jack's most likely not going to get any more spotlights, so it's fine. - Comment by Wildbow on Spacebattles
↑I have it written down somewhere, but I had it down that they were no older than twelve, IIRC. Might have been twelve. -
Wildbow on SufficientVelocity
↑Jack slash is caught in a Grey Boy loop, buried under containment foam, on a devastated Earth. I don't think he's really a contender. - partial comment on Reddit
↑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.
A confrontation had started between a young male and an older one. A fragment of a shard against a very mature shard. The most mature shard in this area, at a glance.
The more mature power was unleashed. A wavelength power, a kinetic transmission.
The entity watched, and it recognized the shard at work. The broadcast shard. One that had been crippled, just like the shard of the female that floated before the entity now. The same shard that had managed communication between the entity and its counterpart. - Excerpt from Interlude 26