Dragon described Marquis as "sometimes rude or casually cruel, but he remained deeply honorable beneath that."  He claimed to "have a lot of respect for people who keep to a particular code, whatever that code might be, and very little for traitors and wafflers." He admitted that he didn't consider himself a good man for following his code.Brandish described him as sticking to his rules without fail, playing "fair" and remaining cultured and polite even in the middle of a fight or when injured. Ingenue claimed that he "switches from the aristocrat to the low born commoner as it suits him. Split personality."
He had exceptional practice in concealing his emotional reactions because of his power, giving him an edge in conversations and negotiations. He didn't always trust himself to lie convincingly, preferring to simply smile.
Marquis was an exceptionally skilled fighter, whose personality and power made him exceptional in turning one advantage into another. In melee, he was able to ensure that every strike he made against Manpower would instead hit one of his weaker teammates if not blocked. He could react fast enough to destroy his own weapon before it hit an "unacceptable" target.
He cared deeply about his relationship with his daughter, having greatly enjoyed it when she was a child.
He described himself as a "worrier" to Amy, but noted that it could be an asset.
As a villain in Brockton Bay, he would quietly execute anyone who failed him. His management style was otherwise remarkably hands-off. He was said to be a callous man, an aspiring crime lord who didn't give a second thought to murdering heroes. Manpower described him as a "pattern killer", a perfectionist with patterns that allowed him to be predicted. He later admitted to himself that he could have left Brockton Bay with his daughter at any time, but he was too enraptured with his role as a super-villain there.
As a cell block leader, he divided up the cigarettes they were given relatively fairly. His men would take first pick of the other supplies, then then auction off the rest to the other prisoners in exchange for cigarettes. They also guarded the television sets, giving everyone a turn to change the channel and preventing them from being broken or dismantled. He noted that he "wasn't a nurturer", with little experience helping those who worked under him, instead trading away those he couldn't use to other cell blocks.
He had long hair that draped on his shoulders. When Brandish saw him in the Birdcage, he had lines on his face. His hair and eyes closely resembled Panacea's, although their nose and brow were different. His brown hair and beard were starting to get strands of gray in them as of Golden Morning. His shoulders, hips and voice were all distinctly masculine, and his voice was confident.
He sometimes wore a beard, and was sometimes clean-shaven.
Like all prisoners in the Birdcage, he wore gray cotton clothing. When the Brockton Bay Brigade attacked him in his home, he was wearing a black silk bathrobe. During Golden Morning, he was seen wearing a fancy-looking jacket and a white dress shirt that had fine lines of black lace at the collar and sleeves. He wore two large rings on a chain around his neck.
Marquis' powers involve the manipulation of bone - his own and, if it became exposed enough for him to see, that of his enemies. If it was his own, he could make it grow or shrink, reshape it and multiply it, although it grew harder the longer it was separated from him. His abilities with the bones of others were limited to simple reshaping.
Every time the bones connected to him break, he feels the appropriate level of unspeakable agony, but he trained himself not to show even the slightest sign of it.
He was remarkably versatile and inventive in his use of bone. He could turn broken-off shards of bone into caltrops with "ultrafine needle points" that would penetrate shoes. He could use his power to burrow underground or through floors and attack from beneath the ground. He could send bone through the ground or ceiling to spring out and trap his enemies with a "cylinder" or cage. He could create a giant scythe from his wrist, or a "ripple of bone" that knocked opponents off their feet. He could create bat wings of bone and fly, manipulating holes in the wings to change air resistance as needed. He was fully capable of taking on a squadron of Empire Eighty-Eight members and walking away. He was also able to take on most of the Brockton Bay Brigade, who would become New Wave, at the same time; although he allowed himself to be injured to protect his daughter.
Marquis had some kind of ability that caused his cuts to seal shut when his bones retracted, even ones he had made by means other than his osteokinesis. However, it seemingly had no effect on on the burns caused by Brandish's power.
He claimed to have grown up in hard circumstances.
Marquis was an independent villain who operated in Brockton Bay, though he was a crime lord he was the soul parahuman making up his group, operating in the early days of parahumans. He reportedly didn't give a second thought to murdering any heroes who got in his way, and was notorious enough that he was still well-known a decade later. He'd lived in the outskirts of the city, residing in a large house in the woods, just beneath the mountains, although this wasn't public knowledge until the Brockton Bay Brigade tracked him down.
He fought Empire Eighty-Eight, and was on record as having murdered Iron Rain, although Jack Slash argued he wasn't capable of it. He fought Jack Slash when the Nine visited Brockton Bay to prevent him from killing women and children. This interested Jack, who tried and failed to make him break his code. He also fought the Brockton Bay Brigade, winning every time. Carol Dallon had a special hatred for him, because he reminded her of the kidnapper who treated her well but was still willing to kill her.
At some point he had a daughter, Amelia Claire Lavere, with an unknown mother, who gave her to him when she was dying of cancer. He raised her for a year, finding the parenting experience enjoyable. He was eventually captured by the Brockton Bay Brigade, defending the cupboard where his daughter was. This was the only occasion he ever lost a fight. Amy would be adopted by Carol Dallon; she did not remember her father, although she did have some vague memories of that time in her life.
He would eventually become the leader of Cell Block W in the Birdcage.
After his daughter had a mental breakdown, she asked to be sent to the Birdcage. Marquis welcomed her there.
He kept Amy safe in his cell block as she weathered her depression, even as it began to damage his reputation. He considered provoking a mutiny so that he could defeat it and prove his strength, or provoking the other cell block leaders into attacking him so that she would be forced to defend him. Luckily, meeting the other cell block leaders prompted her to emerge from her shell somewhat.
He was among those who attended the meeting of all the major powers to defeat Khonsu, and argued in favour of releasing powerful capes from the Birdcage to fight the monster, but the heroes argued against it and he was sent back. He and Amy had successfully deduced that Scion would be the one to end the world by this time.
He was finally let out of prison for the battles of Golden Morning. He worked alongside Panacea in a makeshift hospital, healing broken bones with his power once she had anaesthetized patients.
Following the creation of Khepri, Marquis tried to contain her but was temporarily subsumed as she tried to parse her's new abilities. He was among the first to join her army, alongside the Doormaker and the Clairvoyant. With the depletion of Doormaker, Marquis was active on the final battlefield.
He returned to his old life as a crime lord. Teacher visited him to discuss his dreams of resurrecting an Entity.
His name comes from the old French word for a nobleman between a Count and Duke in rank, and is pronounced in Brockton Bay with the standard English pronunciation of "mar-kwis". 
Wildbow has stated that with his Canadian accent, however, he pronounces it mar-kees.
While his daughter is named Amelia Lavere, it isn't known if Marquis shares her surname. Amelia spent her first five years with her mother before being sent to live with her father and may share her mothers surname.
A popular fan theory is that Iron Rain is Amy's mother.
↑Marquis – Amy Dallon’s father, an osteokinetic, capable of manipulating bones, including his and any exposed bone of his enemy. A powerful Shaker and Shifter, once leader of a villain group in Brockton Bay’s ‘bad old days’, Marquis heads a cell block in the men’s wing. - Cast (In Depth)
↑Prisoner 599, Lung, was dining with Prisoner 166, Marquis. It was a curious match. The two were near complete opposites. Lung maintained a veneer of civility over an almost feral core self, while the Marquis was sometimes rude or casually cruel, but he remained deeply honorable beneath that. - Interlude 10.5 (Bonus)
↑ 4.04.1Marquis took his time rolling and lighting a cigarette, then kneeled before her. He spoke with it bobbing in his lips, "My girl. I'm not a good man. I have rules I follow, but that doesn't make me good. At best, it's one virtue among many I've failed to acquire. I'm rough around the edges, whatever I might play at, and that's plain enough to see to anyone who pays attention. I grew up in hard circumstances, and it's taken me a long time to work past that and earn the respect I get. And I would give that up if you needed it." - Interlude 16.z
↑This was a gamble. Amelia could be the excuse his enemies or more ambitious underlings needed to mount an attack. At worst, he'd die and she would… well, she'd be a resource that was burned up, exhausted of anything and everything she had to offer. If he was able to buy enough time, verify that she was beyond saving, then he could return her to the women's cell blocks, cut his losses and take the resulting hit to his reputation as the only real cost of trying.
He didn't want to take either of those options. He had so few memories with her, from when she'd been a toddler, but they'd stayed with him. He remembered the sparkle in her eye as she saw the princess costume he'd had tailor-made for her. He recalled the look of consternation on her face as she'd sat at his dining room table while she practiced writing her letters. That frustration had become awe as he'd showed her what she could accomplish once she mastered the art, penning out florid letters in cursive with a fountain pen.
More than once, as he prepared tea to share with Lung during one of their long discussions, he'd thought of the mock tea party he'd had with his daughter.
Those moments seemed farther away now than they had in the days before he'd been reunited with her. He would never recapture them, he knew, but maybe he could find other, new memories to share with her. A deep conversation, a father's pride at her accomplishments. -Interlude 16.z
↑"As I understand it," Lung sounded annoyed as he spoke in his heavily accented voice, "You are saying you have no management style at all. You have told me you operated without lieutenants to direct, no product to sell, and of the few servants you did have, you did not punish those who failed you. I do not believe you held control of so much territory in this way."
"Ah, except I did those things. If a servant failed me, I killed them. Whatever it was, they never did it again."
The latent hostility in the room, Dragon noted, was ratcheting up with every exchange of dialogue. Lung was annoyed, and he had an explosive temper. Sometimes literally.
Lung folded his arms, and put down his own tea. His tone was strained as he spoke, "Then I believe you were wrong about what you said before. You do use fear to control others."
"Fear? I didn't kill my servants in front of an audience. [...] I never gave it much thought. Just an easy way to handle any problems that came up." - Interlude 10.5 (Bonus)
↑ 10.010.110.2Marquis had been an aspiring crime lord in the bad old days of Brockton Bay. It had been a time when the villains had been flocking to the city to profit off the booming tech and banking sectors, to recruit mooks and henchmen from the city's unemployed dockworkers. It had been an era when the heroes hadn't been properly established, and the villains had been confident enough that some didn't give a second thought to murdering any heroes who got in their way. Marquis included.
Marquis had been an osteokinetic. A manipulator of both his own bone and, provided some was exposed, the bones of his enemies. He'd been notorious enough that she'd heard about him despite the fact that he'd been arrested more than a decade ago, that the city and the public had remembered him. He'd lived in the outskirts of the city, residing in a large house in the woods, just beneath the mountains.
To all reports, the man had been heartless, callous.
What else did she know about Marquis? She vaguely recalled Uncle Neil talking about the man when he'd been talking to Laserdream about villain psychology. There were the unpredictable ones, the villains who were hard to stop because you couldn't guess where they'd strike next, but who were less practiced in what they did and made mistakes you could leverage against them. There were also the orderly ones. The ones who were careful, who honed their methodology to perfection, but they repeated themselves, showed patterns that a smart hero could use to predict where they struck next, and often had rules or rituals a hero could turn against them.
Which wasn't to say that one was smarter than the other, or that one was better. Each posed problems for the local authorities and capes. Marquis had fit into the latter category, the perfectionists, the pattern killers. He'd had, as Neil explained, a warped sense of honor, underneath it all. He didn't kill women or kids. - Excerpt from Interlude 11h
↑ 11.011.1"Which cell block are you in?" this question came from a heavyset woman that looked more like a middle aged soccer mom than a prisoner. Lung noted, however, how each of the other girls that were on guard turned to listen when she spoke.
"W, ma'am," he spoke, taking extra care to not offend.
"Marquis runs your cell block, still? Divvies up the cancer sticks from his food crates fairly enough?"
"Yes." Lung reached into his pocket and retrieved a half-carton of cigarettes. - Excerpt from Interlude 6
↑Not every block worked the same way, though the layout and the scheduled drops were the same for each. The advantage of Marquis' arrangement was that it kept his people relatively happy and it kept them in their place. The lieutenants and Marquis himself got first pick of any of the items from the supplies, but nobody truly went wanting, so they generally agreed with minimal complaint. - Interlude 16.z
↑Tidy in appearance to the point of caricature, Spruce stood guard by the televisions, helping ensure that Block W remained the only block with a full set of working sets. He would ensure everyone had a turn to choose the channel. Whimper was overseeing the auction. Everyone had already received their share of the cigarettes, which served as currency for bidding over the more in demand items of the supply drop. There were less new blankets than there were people in the block, for example, and each drop only included maybe three or four books; always one classic and two from the recent bestseller's lists. Good reads and books with raunchy scenes could be resold to other prisoners for a decent amount, and they would exchange hands until they were too worn to keep. - Interlude 16.z
↑She wasn't the first of her kind that he'd seen. A hollow shell. Tabula rasa. A blank slate. She wasn't sleeping at night, not easily, and she had frequent nightmares.
He'd seen others, had had two appear in his cell block, delivered by their tinker overseer. Except he wasn't a nurturer. He had no experience on that front. He'd done what he could to see if he could wake them up from the neuroses that gripped them, and then he'd bartered them away to other cell blocks when he hadn't seen improvement over one or two weeks. People who were damaged on this fundamental level tended to go one of four ways. They recovered, which was rare; someone filled the empty vessel with an ideology; they were used as a resource, cared for so their talents could be exploited; or they were spent, burned up of whatever they had to offer, be it making things or violence.
He wished he'd tried his hand at fixing the two who Dragon had delivered to his block. Maybe he'd have a better idea of how to deal with Amelia if he had. - Interlude 16.z
↑ 15.015.115.215.3A man at the side of the room stood straighter. Marquis. His hair was long enough to drape over his shoulders, his face clean-shaven by contrast. He had a fancy-looking jacket folded over one arm, and a white dress shirt that had fine lines of black lace at the collar and the sleeves he'd rolled up his arms. Two ostentatious rings dangled from a fine chain around his neck; the chain had a locket on it, suggesting he'd added the rings as an afterthought. To keep them out of the way while he worked, perhaps.
"What is it, Amelia?"
For another man, the combination of physical traits and the style of dress might have led to someone mistaking them for a woman. They might have come across as effeminate.
Marquis didn't. Not really. When he'd spoken, his voice had been masculine, deep, confident. The cut of his shoulders and chin, his narrow hips, was enough that I couldn't expect anyone to mistake him for a woman. I wasn't the type to go for older guys, I wasn't even the type to go for effeminate guys. But I could see where women would go for Marquis. - Cockroaches 28.3
↑ 16.016.116.216.3Marquis was next to arrive. His brown hair and beard were just now starting to get strands of gray in them, wrinkles at the corners of his eyes.
He'd been one of the scary bastards of Brockton Bay well before the Undersiders were even on the map. A guy who could go toe to toe with a full squad of Empire Eighty-Eight and walk away. He'd been successful enough to pay for hirelings and ruthless enough to execute them for failures. His path to the Birdcage had been very similar to the path that had almost taken me there; so many violations of the law that the three strikes rule had been left well behind him by the time the good guys finally won. - Extinction 27.3
↑Marquis Skiled osteokinetic, produced and re-shaped a variety of bone constructions, could affect enemy's exposed bones. - parahumanList, bolded edit by Wildbow.
↑"There are others who stand shoulder to shoulder with us, but queen is the wrong word, Administrator. The champion, the high priest, the observer, the shaper, the demesnes-keeper[...] The shaper and demesnes-keeper clean up after we are all done here, one way or another. So it goes."
↑"Can I not say you are a kindred soul? Someone who fought against the Empire Eighty-Eight, in a different era?"
Marquis shook his head, "Not entirely. I have some reasons to be concerned. In one of my fights with Empire Eighty-Eight, I executed one particularly irritating young woman. Iron Rain, I think her name was? No matter. It turned out she was Allfather's daughter. The man called a meeting, and swore he would wait until my daughter was of similar age, that I grew equally fond of her as he had his own daughter, then murder her. So I knew how he felt."
Dragon turned her attention away from the audio and video streams. She checked the records, and true enough, Marquis was on record as the killer of Iron Rain. It was impossible to verify the rest of the story. - Interlude 10.5 (Bonus)
↑ 27.027.1"It's the name you were born with. Imagine my surprise when I found out your relation to Marquis. In my last visit to Brockton Bay, I crossed paths with each of the major players. I met the man. I must tell you, Amelia, he was a very interesting character."
"I don't really want to know."
"I'm going to tell you. And I have another motive, but I'll get to that in a moment. Marquis was a man of honor. He decided on the rules he would play by and he stuck to them. He put his life and limb at risk to try to keep me from killing women and children, and I decided to see if I could use that to break him. I admit I failed."
"No. What I'm saying is that Marquis would not have killed the girl, even under duress; that was one of the rules he set for himself. If he was going to violate that rule, he would have done it when I'd tried to break him." - Prey 14.10