Heaven/Hell/Earth brainstorming notes
Heaven and Hell are alternate dimensions parallel to Earth's. Powers in both worlds are a natural occurrence, and the differing appendages are normal as well. It is considered an abnormality to look human. The 3 rulers of both worlds were not born into the job, technically, but they are different from the others in such a way that it was considered best if they were appointed to their positions of authority. In Heaven's case, they were elected in a desperate attempt to unify the planet after a massive and devastating war destroyed it and its inhabitants. For Hell, it was a paranoid sense of foreboding that gripped the population to thrust the master rule into the hands of the most powerful, intelligent and resourceful (which turned out to be a wise decision in the long run and so they stick by that rule at all costs). Because of their specific gifts, they are the only ones fully aware of Earth's dimension, and in time Earth becomes aware of theirs as well. Only two of the appointed ones visit the planet regularly (Lucifer and Azrael, made to harvest Human Souls). Baphomet and the male Michael also have the power to Shift dimensions and so become their escorts. The Anointed from both worlds are harvested human Souls and there will ALWAYS be 144 000 in existence.
Heaven and Hell are aware of eachother, and there is some socialization between the 6 appointed ones. They agree to disagree and stay out of eachothers' affairs. Earth wages a war against Heaven and Hell eventually, prompting Beelzebub and the female Michael to create extra living beings to keep the humans in check and guard them (Hell's Experiments and Heaven's Archangels, led by Baphomet and the male Michael respectively). There is a 4th dimension alongside all 3, which they refer to as the Spiritual plane. It is in this universe that Lucifer and Azrael are able to affect any human, angel or demon Soul, and only they can Shift to it. For this they are hunted by the humans and are feared by their own people.
Before the massive war, Heaven was the most technologically advanced, with Earth a close second and Hell last, nearly stuck in an era similar to the Dark Ages. Earth has no 'appointed' rulers like Heaven and Hell because there is too much debate going on about who should be in that position. There is no special way for a human to be better than its peers. They become aware of alternate dimensions when Lucifer gets caught killing someone, and escapes by rather undeniably extraordinary means. That's when the hunt for Lucifer (and later Azrael) begins. The humans want to dissect them at first, but eventually they just want to kill them. The Humans begin to experiment in genetic mutation when they manage to Shift imps and minor angels forcefully onto the planet (killing them instantly).
The experimentation on the angels and demons opens up a particular market among the wealthy, eventually trickling down into the masses. Wings become a commodity, and halos ripped from the dead hosts are made into fashion accessories. There is a marked preference for feathered wings over boned ones, as they are less likely to rot off after surgery. The growing number of simulated 'angels' make the female Michael quite restless and shatters her composure. The stress on her planet only increases, and the fragile minds of the angels can't handle it. There is a type of insanity plague at one point, making the angels continuously feel the need to molt.
Lucifer and Azrael are no longer tied to Earth's fate, nor are they the catalysts for the end of Heaven/Hell like in the old story. The end of the story is the Human's attempt at completely bombing the other planets. They fail so bad they destroy their own.
If you have not caught on yet, Earth, Heaven and Hell are not seperate dimensions, they are seperate points in time for the same, single planet that managed to make contact. :D
Chronologically, from the furthest back in time to the furthest ahead, it's Earth, Heaven, Hell, with a difference of about 2 500 years between Earth and Heaven, and 7 000 years between Heaven and Hell. Shifting turns out to be a power to shift back or forward in time, not shift across space. The atomic bombing is what creates the mutant powers phenomena in Heaven, along with deformities and the lack of fauna and flora. It also permanently affixes the 'winged' characteristic to the Human's DNA. The only real alternate dimension is the Spiritual Plane.
After the war, all records of human civilisation are lost, and the few remaining humans, turned into 'angels', awaken to find their planet nearly barren many years after the atomic bomb went off. The first angels are not pretty, disfigured by the explosion and years of doing absolutely nothing due to the amnesia that followed. The first generation of angels has a regular human lifespan, and can still bear children and need to eat for sustenance. Their survival is completely accredited to their muscle memory. Their progeny are still able to reproduce, but there are more miscarriages. They rarely need to eat, a trait eventually weaned out of their DNA along with fertility over the span of nearly 30 generations. This is both a curse and a blessing, as the food supply is exhausted. Their lifespans also lengthen, a trait still unexplained. The angel's bodies begin to transform, some lengthening, others shrinking, yet more becoming darker or paler of skin than humanly possible.
They slowly come to realize that they have new abilities. The most common is 'flight', but it's actually only hovering. Second most common is modifying the location of the halo. The rest of the powers are more superficial than useful, such as conjuring illusions, masking their appearance, telekinesis, etc. The rarest powers are Shifting, Shapeshifting, and Impeding (blocking all senses, or a sensory overload). In order, Azrael, Raziel and Michael are born with these abilities. They are not related. The population realises their potential almost before they do, and they become revered icons in Heaven. Michael leads the three, as she was given scars on her head and halo (something never seen before). She has a very obscure past and never speaks of how she got them, though she occasionally references her 'mother' in conversation.
A caste system is put in effect not long after the Sisters are appointed. The smallest angels are designated as Minor Angels, the regular sized ones as simply Angels, the larger ones as Major Angels and the Sisters as Grand Architects. Intelligence and powers are evenly spread amongst the different types, though in appearance the Minor Angels are very stereotypical while the Sisters look nearly human.
From the moment the humans awoke after the bombing to the point in time that Michael comes to power, the development of the angels is all about fighting for survival and adaptability. By her time the Angels are comfortable in the way of living they've figured out for themselves, and they continue living in their system for many decades before the trouble with Earth begins.
By the time the Humans destroy themselves, the Sisters have died along with the Archangels, leaving the Angels leaderless and cut off from Earth and Hell. Still fragile of mind, stress and radiation from the glimpse of the atomic blast causes them to shed their feathers and triggers yet more mutation. Horns and tails start sprouting on certain individuals, and many gain the ability to reproduce.
Only one piece of the Sister's legacy remains at this point, the chief Archangel Michael. He goes into hiding very soon after they die, heavily injured. He does not appear until Leviathan is appointed to power nearly 3 000 years after the fall of angelic society. Nobody knows who he is, only that his scars are a sign of authority (which he exploits) and soon appoint him to power as well. Lucifer isn't born yet at this point. Michael (calling himself Beelzebub) grows into his role as dominant leader, mostly ignoring Leviathan.
Lucifer is the progeny of two Major Angels, now referred to as Major Demons. He becomes quite unruly and prone to violence. He is appointed after he accidentally kills another Major Demon, recognized for his power to effortlessly strike down a near-immortal. Beelzebub and Leviathan do not take kindly to this addition, but call him their Brother anyway. He becomes a part of the trinity about 1 000 years after Beelzebub rises to power.
It isn't long until Lucifer realizes he's inherited the power to Shift, and makes many visits to Earth. This is where he meets Azrael for the first time. They get along fairly well at first, establishing a connection between Heaven and Hell's appointed Trinities. They eventually go their seperate ways as Michael and Beelzebub do not get along.
Beelzebub remembers everything from the moment he was created, and does not wish to associate with Michael. He dislikes seeing his former, subservient self even less.
When Lucifer betrays Heaven and Hell's existence to Earth's officials, Beelzebub immediately restricts Lucifer's involvement on Earth, giving him a guard (Baphomet) to prevent any more incidents. He creates 12 guards for himself, fully aware of what will happen on Earth. He counsels Michael to establish a guard as well, wanting to ensure his existence.