Hatchet Face hated parahumans, and only joined the Slaughterhouse Nine because Jack Slash convinced him he would kill more capes as a member. He had a particular dislike for brutes. It can be safely assumed that he possessed almost no sense of irony whatsoever or a very developed one. As Bonesaw claimed he was never very bright, it was probably the former.
Hatchet Face is a parahuman with superhuman strength and enhanced durability, as well as the ability to nullify the powers of parahumans nearby. This combination made him a highly efficient cape-killer, as any close-quarters battle between him and another parahuman essentially turned into a fight between a regular human and a Brute.
His durability has been stated to allow him to survive being run over by a steamroller, observed evidence has a clone being tossed by the head over several blocks and standing up unscathed and barely noticing attempts to cut his throat. His strength allowed him to move incredibly fast for his frame and allowed him to swing his namesake hatchet through a car if need be.
His aura instantly nullified the power of anyone inside it.
He was vulnerable to attacks and ability effects from outside the range of his powers, as Cherish used to her advantage during her induction into the nine. Tinkers were largely unaffected.
Having triggered from an injury experience involving parahumans, he announced himself by killing a superhero during a live interview. He became a serial killer specifically targeting capes, and especially Brutes. Jack Slash convinced him that the easiest way to do this would be by joining the Slaughterhouse Nine.
Hatchet Face was killed by Cherish as part of her attempt to convince Jack Slash to let her join the Nine. Bonesaw combined his corpse with that of Oni Lee in order to create a lobotomized robotic puppet called Hack Job.
Bonesaw created nine clones of Hatchet Face for the Slaughterhouse 9000, with another used in making a special combo-clone dubbed Tyrant. Several clones were killed with great effort by the Chicago Wards and people like Chevalier and Tecton.
↑ 1.01.11.2Yeah, again, think about the person, not just the powers.
I've stated the types of triggers for a trump ability (canceling powers) and for a brute ability (super strength/durability/extra mass). At the most basic level, you can conclude he was hurt very badly by a parahuman. He probably has a grudge/obsession, and that limits him. In execution, he's probably very much like Crawler, but he's a parahuman-seeking missile, going after the nearest available parahuman that might remind him of the man who maimed him and made him a monster. Quite possibly brutes, just because it fits.
Prior to Jack, he hits a new city, stalks for a while, keeping an eye out for a chance to go after the biggest, strongest capes around, ideally by blindsiding them, because he's not that fast, and it defeats the point if they can just run. He hits them where they think their safe, or their guard is down - at news stations where they're giving an interview, at PRT offices, or interrupting fights to kill both the parahumans that are fighting.
Jack finds him at a point of weakness, though - either Hatchet Face had a few too many lost fights/escaped parahumans, or Hatchet Face tried to kill Jack and failed. Jack convinces him that he'll kill far more parahumans if he joins the Nine, and the rest is history. - Comment by Wildbow on Spacebattles
↑Hatchet Face Enhanced strength and durability, aura nullfies powers of those nearby. Slaughterhouse 9 - Parahuman List, Bolded edit by Wildbow
↑ 5.05.1Hatchet Face was a brute. His claim to fame was attacking a news station where a superhero was being interviewed and brutally cutting the hero down, stripping them of powers and then butchering them with swings of his namesake axe. The segment never made it onto the airwaves, but the audacity of the deed sparked attention. By lowering his enemies to a baseline level and then going after them with his still-enhanced strength and toughness, he gave every cape cause for worry. Triggering when he was injured by capes in a careless attack, he started out as a brutal vigilante, but quickly left that mission behind in favor of a simpler, brutal agenda of taking what he wanted and cutting down the biggest boys and girls around. - Another comment by Wildbow on Reddit
↑Hatchet Face – The bogeyman of the cape community and a member of the Slaughterhouse Nine, Hatchet Face is a large, strong, nearly-invulnerable cape who strips nearby capes of their powers, stalks them and chops them to pieces with his namesake axe. - Cast (spoiler free)
↑Hatchet Face (Deceased) – Onetime member of the Nine, supplanted by Cherish. A musclebound brute favoring his namesake weapon, Hatchet Face generated an aura that shut down the powers of others, allowing him to stalk and murder even superior capes with his enhanced strength and durability. was made into an artificial siamese twin by Bonesaw, melding him with Oni Lee to become ‘Hack Job’. - Cast (in depth)