Easily the friendliest of Hags (not that you would want one as your friend of course), though only if you can provide them with good, ripe, and interesting bones...
Marrow Hags are of course, obsessed with all things to do with death, particularly and especially Bones. They love all things to do with bones, the stories they tell, the diseases that can contort them into all kinds of forms and shapes, the charms they can carve from them, the voices they can force them to speak in, the control a good piece of bone can grant over a person. And if you can offer them a bone of sufficient "quality" (the definition of which is idiosyncratic to each Marrow Hag,) then she will gladly suffer your company through gritted teeth and graciously allow you to keep hold of your own skeleton for a while more.
If you were to irritate the Marrow Hag, or heaven's forbid attempt to fight one, you would find your own bones turning against you; thin, ethereal strings reaching from within your limbs to the Hag's fingers as she makes you dance and twirl, cackling as she does so, before she forces you to break your own limbs.
Marrow Hags are also self-proclaimed mistresses of Necromancy; not the animation and negative-energy manipulation practised by the more bombastically dour of mortal villains, they will declare, but the true, primal meaning of necromancy, the contact and manipulation of the souls of the dead. Forcing bones to talk and give up their secrets; the transference of the energy of the dead to the living to induce sickness; the forcing of spirits into cages such that their words can be used against their will; this is the Hag-magic practised by Marrow Hags. The most powerful of Marrow Hags can practice any rite of necromancy you might be able to consider. But treat her well and give up plenty of bones. Where as other Marrow hags can only make you move against your will, Grandmother Marrow Hags can break and deform your bones with a snap of her fingers; distort them into any shape she wishes; meld your joints into a single solid; pull your ribs from your chest with a crooked, beckoning finger...
Each Marrow Hag will also keep with them a bundle of bone-charms and scrimshaw, all run-about with carvings and sigils traced into the web of ivory. These are their protection and insurance. Some will prevent blades from harming their flesh, some turn the luck of their enemies against them, some can be broken to manifest powerful magics. It is best to be well prepared if you plan to face a Marrow Hag.
That being said, if you offer a Marrow Hag a truly special bone, say the infected scapula of a dragon, or the scarred rib of a giant, or a titan's knuckle carved into a cup drank from by a lineage of mighty orc chieftains, then the Marrow Hag can be persuaded to teach you some of her bone-charm arts, tell you how to score and groove the bone, what shapes to trace, the words to mutter as you do so, the incense to burn as you go.
Marrow Hags will do anything they can for good bone...
In a Byenic Hag's house, you will find many jars, and inside those jars (perhaps you can guess by the stench and flies) sits a soft lumpy pile of rotten and runny meat. If you cannot find her in her home, perhaps you will find her just outside, crouched, and salivating over the corpse of her last kill. She has been there three days, though you do not know that. She can't touch the body until its soft with rot.
Meat and Rot are the two great loves of Byenic Hags. They love them so much that they have learned how to rot with a touch, though they only do this to creatures they are hunting; its less 'pure' than naturally set rot, or so they say. Carrion is so much more delectable when untainted by magic, according to them at least. Their other Hag-Magics sprout from this fundamental power, and with a look they can instil nausea and sickness in creatures, they can spoil food in their presence, and degradable items will disappear rapidly in a heap of muck if the Hag wishes it. Sometimes, even iron and steel can be caused to rust and corrode under a Byenic Hag's grip. The mightiest of all Byenic Hags can transmute the very ground itself into a steaming and stinking quagmire of fetid flesh.
Byenic Hags in their element are endurance hunters; they will use a burst of energy at the very start of the hunt to set a rot in their prey's flesh, then merely track and stalk until the prey is brought low by the impurities and miasmas breeding within them. Then when the flesh is sloughing and soft, the corpse is dragged back to the Hag's hut to ferment and mature further. To touch unrotten meat would be disgusting to the Hag, and indeed their own flesh is calloused and scabbed all over. If one has been sat or crouched for a long time, you would be able to hear the crackle of dead flesh when she stood, and if that were not enough to make you gag, the smell would.
Byenic Hags will often eat the foul meats they gather and soften raw and plain, but sometimes, they will make an extra special effort, occasionally even inviting other Byenic Hag's to partake. They will lay out spreads of horrifyingly corrupt meats; stews of soft, runny flesh; quivering heaps of muscle, seasoned with fungus and crumbling woods, mosses and lichens. They will scoff it down with aplomb, the blackened and sickening morsels staining their lips and faces.
Some Byenic Hags take their fascination even further, and will create companions for themselves out of the meats they collect. Bone skewers and slabs of pallid muscle are stuck together haphazardly, and all animated with Hag-Magics. The result bears a resemblance to a flesh-golem, but it is altogether more unwholesome and sickening. Worse, the existence of one will increase the amount the Byenic Hag mistress will need to hunt, lest her Meat-Idol collapse as its flesh sloughs away and rots utterly.
Red Hags bear some semblance of similarity to the Byenic Hag, but where the Byenic hag is gristly, grey, and scabbed, the Red Hag is raw, and the colour of bleeding flesh; and where the Byenic Hag eats rotten meat, Red Hags eat the meat of men.
They are like something out of a nightmare. Out in the hills where no-one else is, she stalks you through old abandoned shacks, drooling at the thought of tearing your meat from your bones while you're still screaming. Red Hags of all hags lack any of the usual Hag-Magics, but they instead have a devastating arsenal of natural weapons in their teeth, talons, and raw brute strength. Their flesh also mends preternaturally well, healing even grievous wounds in minutes or shorter, though it wouldn't save a Red Hag from the cold grasp of death. Usually. Some unusually powerful Red Hags have been known to have been definitively killed, dismembered, or burned, and yet returned to exact bloody vengeance. Very bloody vengeance.
All Red Hags also carry some kind of weapon; often an axe or hatchet, sometimes a cleaver, or machete. Either way, they are all just a bit too large to be comfortable around them, they are all rusted and stained the old stale brown of blood, long since dried. The Hags especially love to drag them behind them as they slowly stalk prey, the metal grinding on the stone floor.
These weapons have been passively enchanted by being in the Red Hag's presence, and some of the fear the hags inspire in their prey has soaked into the weapon over time, and even seeing the weapon can be too much for some. Even after the Hag's eventual demise, the weapon retains this unconscious aura of despair and gut-wrenching terror.
When fighting a Red Hag (such an altercation is unavoidable with these barely civilised beasts) there will be little in the way of direct confrontation. Mostly you will be stalked; the Red Hag is sure to know all the locations near her home in uncomfortable detail, and she will surely know the best hiding places, the best ambush spots, the best places to come smashing through the crumbling wood walls with her talons extended to gouge out the flesh of your throat. Even in places unfamiliar to her, she will probably be able to turn the terrain against you.
The Red Hag's most profound weakness is her lack of intelligence. Her only real area of expertise in knowledge is in anatomy, many other things are a mystery to her; not that she cares. She is unreasonably cunning and wily, but if you can lure her into a trap she cannot escape with brute strength, she will likely remain trapped. Of course, even luring her into such a trap is tricky to begin with. Especially when she is more often than not the hunter, and when she can be altogether unpredictable.