You'd be looking at a necromancer. Certainly not a demon hunter.
No. Hell no.
Necromancy healing? Sure thing. No problem.
Demonic corruption burning destruction healing? No way. Absolutely not. It's rather against the theme of the whole thing.
Demon HUnters are somewhere between mages , warriors, warlocks and rogues.--- Demon Hunters and Shadowy Warriors(From WoWPedia Class theme) ---> Shadow can "deal damage, heal , shield" so we can use the theme to build a healing spec based on that... Demon Hunters are also capable to Parry ( Warriors ) ,DHs can channel Chaos and various magical energies throught weapons (unique) , can use Fel(warlock) , Flame(Warlocks, Mage), Shadow (Death Knight, Warlock) ,Arcane (Mage) , can dodge(rogues).
Paladins are warriors of the Light. Demon Hunters are the Warriors of the Darkness(Shadow or whatever). No guys this doesnt go against the theme.
It's just not realistic. Demon hunters will never have a healing spec. It's just not part of their set up or character. They are too solitary and committed to demon hunting and killing undead. to be a beneficial healer to a group, it would be too radical a change. something they didnt have before all of a sudden thrust into the class.
shadow healers just seem to be a bit of an oxymoron. You could argue a necromancer would use absorbtion techniques to drain life forces from foes and channel into an ally or for every enemy killed healing is stacked to unleash, or every corpse has its soul aborbed and distributed. Heck you could even say that for a necromancer to heal in its healing spec, it has to cause damage to a enemy like a disc priest.
Warlocks don't have "healing abilities" as such as they have leach and siphon effects that drain and ebb away living things to restore them. you can argue it's healing, ok but it's more a drain or life force absorb.
Shamans are natural spirit healers, medicine men, witch doctors anyway so they are bound to be able to heal.
mannoroth is just one of the legions lieutenants. He isn't the leader of pit lords.
Anyway mannoroth was made a lieutenant after Kil'jaeden found him. Someone else became the leader of the pit lords after his promotion.
Anyway, mages have a self heal ability but they don't heal with fire so the point is moot. warlocks don't heal with fire so the point is moot.
Demon hunters won't heal.
And a class that is arcane, fire, nether, dark, shadow, melee, tank, healer, dps is called a me'dan.
It's pretty safe to say now that you have exhausted most possibilities and really are clutching at straws.
Again, this concept is already in the game. Shadow Priests heal themselves and others using Shadow magic and have a vampiric aura (of sorts). It makes sense for Shadow Priests to have this ability. It makes NO sense for Demon Hunters to have it. If DHs ever appeared in WoW they would more than likely either be pure DPS or 2 DPS and a healing spec. Demonic magic simply doesn't lend itself well to healing/restorative magics.
At this point, the only real option left in terms of unexplored class themes is Mechanical/Technology. Not only can that theme tank, heal, or do DPS, but it wouldn't step on the toes of any existing class.
I've proposed broadening the class concept before when people have tried to shoehorn healing into demonhunters. If they were a broader class like "Slayer" that included dragon slayers, demon hunters and shadow hunters; and each spec took some powers from their respective target in order to fight it, then you'd have something. Though shadow hunter is kind of taken up by shaman stuff at the moment.
I would like to see a class that uses its own health + some mana to cast all of its big/aoe heals, and maybe have a secondary resource that stores Health globes that you can use similar to rune tap to get a huge amount of HP back every so often to set the balance.
“What can be asserted without proof can be dismissed without proof.”
-Christopher Hitchens, 13 April 1949 – 15 December 2011