The Nether-Bound is a symbiotic hybrid of a human (Jenna Carson) and a netherbeast (The Unformed Hunger) - one of the eldritch, protean denizens of the deepest, darkest pits of the Netherworld, serving as that plane's apex predators. Even when in civilian attire, black netherflesh can be seen criss-crossing her body. Even what appears to be her hair is actually a facsimile of such, merely another extension of her symbiote. Given the nature of said symbiote, it can take various forms around her as she desires, which she can use for combat purposes - such as covering herself in netherflesh armour and extruding various negative-energy-infused tentacles to slam and grab her foes - or for civilian purposes - such as changing her hair style on a whim, or forming amusing costumes around herself. In addition, enclosed folds of netherflesh form five-dimensional pockets, which Jenna uses liberally to carry anything she could possibly need or want on her person. Including cheeseburgers. She is never without her cheeseburgers.
Netherbeasts, being the apex predators of the Netherworld, like to eat. A lot. They can, in fact, eat just about anything, but they all have their preferences, which they tend to stick to. In the Netherworld, their typical prey consists mostly of lost souls which have managed to escape the gaze of the Drudges or other psychopomps; souls, as it turns out, are rich in most things which a given netherbeast might prefer to eat, and are readily available. But they have been known to also eat other denizens of the Netherworld - especially if a given netherbeast's tastes happen to skew towards the more corporeal - or even resort to cannibalism if they are especially starving. The Unformed Hunger has a taste for what can only be called power or energy, of any and all kinds. Kinetic, potential, radioactive, electrical, chemical, magical, and so on. Within that category, it especially favours entropic and negative energies, such as that of the Netherworld itself, or the sort exhibited by Nictus and Warshades. The Nether-Bound has been known to slurp the Nictus right out the Council's Galaxy soldiers, as if they were oysters... The Unformed Hunger's least favourite type of energy is anything within the conceptual framework of 'light', whether that be mundane electromagnetic radiation such as lasers, or especially magical forms of light. This is due to such light being the main weakness of netherbeasts. Divine light is the only thing in existence known to be able to actually kill a netherbeast - therefore, it is also the Nether-Bound's primary weakness as well. Due to conceptual bleed, however, even completely non-magical forms of luminous assault - such as laser fire or some kinds of energy and radiation blasts - are capable of causing her great harm and pain, even up to incapacitation.
That said, it's certainly not easy to incapacitate the Nether-Bound. Netherflesh is quite tough - not 'invulnerability' levels of tough, but enough to let her wade through metahuman combat with ease - yet that's not what really makes her such a nightmare to fight. It's the rapid and complete regeneration which makes netherbeasts - and thus the Nether-Bound - an unwise choice of foe. The Nether-Bound has, so far, come back from everything that has been thrown at her, up to and including dismemberment and disembowelment. She is an implacable and unrelenting opponent in combat, and is rightly feared by lesser villains across the Rogue Isles.
Another thing to note about Jenna's appearance is that she is never seen without her pink belt. The jewel set in the buckle has a clear abjuration aura to those who can detect such things - it helps Jenna stay in control of her symbiosis.
Jenna's been through a lot, over the past couple years. In April of 2020, after a year of research, she performed a summoning and pactbinding ritual in order to change her body in ways which the American healthcare system proved too expensive to facilitate, for a daughter of working-class parents. Her transition was agonizing, and the form they promised her is great. She finally felt comfortable in her own body, but suddenly had a whole whack of new problems, such as 'coming out to her parents,' 'explaining to her parents what the hell she just did,' 'updating her legal name and gender,' and 'getting arrested by Longbow for unlicensed metahuman law enforcement activity.' After giving her a stern talking-to, the Candycanes pretty much press-ganged her into registering as a hero. She was very tentative at first, afraid of what her new symbiote might influence her to do - or that it might take control completely. That changed after she joined her first supergroup, where a certain Warlock gave her the gem she now wears on her ever-present belt. Things were looking up for a couple of months until she got kicked out of that group for reasons that amounted to 'the autistic tentacle monster is not good PR.' The next group she joined was a real doozy, with frequent infighting and disasters. Her stint in that group only ended up being a few months as well, at which time they got bombarded by frame job after frame job after false-flag operation by the billionaire-helmed shady tech firm they were investigating. That group caved and dissolved under the pressure - but not before a curious final mission when that very same billionare posted a bounty worth millions of dollars for the rescue of civilians - who ended up being test subjects - from a facility of his which was under attack from Crey Industries.
The other former members of that now-defunct group used their shares of the bounty to clear their names and move on. Jenna decided that she didn't want anything to do with the establishment anymore. She had, in truth, held anarchist ideals the whole time - but she'd been on thin ice at first, and genuinely wanted to help people and save lives. Now she was a fugitive, and fed up with the whole game of deferring to authority and sucking up to corporate interests which the 'proper' capes played. At the suggestion of a friend, she decided to take her chances in the Rogue Isles - and found cape work there to be more... rewarding. People there just assumed she was yet another villain or merc, and tended to offer bribes for their rescue. From most people, she refused. They needed the money way more than she did. But when she happened to come across a rich woman stuck in the sewers of St. Martial, who offered her an entire bank account...? Why not, right? Hundreds of thousands of dollars was absolutely worth the periodic Arachnos kill-squads, in her eyes. And fighting off said kill-squads was something she, at this point, was a hell of a lot more emotionally equipped to deal with, rather than trying to navigate her autistic ass through the PR game back in Paragon. And yes, she was acutely aware of how screwed up that mindset sounded.
Eventually, the kill-squads stopped coming. The Spiders had decided she wasn't worth wasting so many resources on... and she'd become an established part of the ecosystem, as it were. A bogeyman. Something which Arachnos could spin to their advantage - much to her chagrin - to keep lesser villains in line: "Stick with us and do as you're told, or the Nether-Bound will get you!" But not long after this, she was contacted by a mysterious old man, who was putting together a team in the Rogue Isles. One of the only - if not the only proper metahuman squad of do-gooders in the Isles...
Or at least as good as one can do, out there...
The Doom Guard.