The Gatekeepers... all will be explained in time.

'Oh no, not again.' Polaris Black groaned, finding herself in a darkened forest, where the shadows loved to flit around the murky tree-trunks.
'KYPRIOTH!' She yelled, annoyed. She knew he wouldn't answer, and he didn't. This nightmare was her own. She tossed a piece of her long, ebony hair behind her shoulder angrily, as she didn't like being stuck in nightmarish lands alone, without his annoying commentary running through her ear. Her dark blue eyes glinted from her porcelain-pale face, surrounded by a thick fringe that was her eyelashes, as they darted around, looking for any sign of life. All she found was a black raven, sitting there calmly starring straight at her. She decided to ignore the contemptuous beast, and to keep looking around.
'Sirius?' she called carefully, and was relived when nothing moved, except the damnable bird.
' JAMES, LILY?' She began to call names at random, seeing if any of them were here with her. She received no answer.
'REMUS, ATLANTIS, RAKURIL?' Still nothing.
'SELENE…?' It took all her courage to choke out the last name she was going to call. 'MORGAN?'
As if on cue, a smoky figure appeared seated by the base of one of the trees. The figure was a young woman, barely out of Hogwarts, staring with glassy green eyes at Polaris. The woman's long mahogany hair, normally pulled back immaculately in a headband, was a mess, flowing over her shoulders and hanging in her face. Her robes were ripped and torn, with burn marks across her chest. Instinctively, Polaris knew her Slytherin friend was dead, although her heart kept yelling that it was false. There was nothing she could do about it but mourn. Her eyes caught sight of a silver medallion, the one she herself removed from Morgan's neck when they found her dead. It was etched with a new moon symbol, the silver tarnished and darkened on its face.
'So passed Morgan Le Faye' she murmured, her voice thick with tears. A flicker in the corner of her eye made her turn, and she wished she hadn't. Sprawled out by a tree was another young woman, barely older than Morgan was. She was dressed in black velvet and brocades, a silver tiara framing her pointed ears. Her bright blue eyes were also open, staring straight ahead, determination forever frozen on her face. The pale head was cushioned on a pillow of crimson curls, Rakuril's natural color, as Polaris painfully knew. Polaris let out a sob at the new arrival, because she had seen her friend's death twice, and both times, she had been powerless to stop it. Another amulet glimmered from Rakuril's neck, this one etched with a half-moon, half-tarnished and hanging from a black ribbon.
'Raku…' Polaris hiccuped, turning her face away. Suddenly it was all gone. The dark forest, the visions of her dead friends, it was all gone into swirling black mist. Polaris's solitude didn't last for long; another vision embraced her and deposited her roughly on a white marble balcony overlooking a sunset and the sea. Infront of her, another tall young woman stood, her snow-white hair done up in an elaborate style, and sprinkled with diamond hair ornaments.
'Atlantis.' Polaris sighed, thankful to see a familiar living face. The woman didn't acknowledge her presence, but instead ran her hands along her white and silver two-piece dress, smoothing the wrinkles from it. Sea green eyes peered from her tan face, concentrating on the horizon, wistful and contemplative, as if wishing her predicament away.
'They still mean to go through with it.' Polaris whispered, knowing full well that no one would hear her. 'They still mean to go through with your coronation as Princess, besides all that has happened.' Atlantis sighed and reached up to the back of her neck, unclasping her Egyptian style collar. The front had an etching of the full moon, shining silver among the gold.
'I'm so sorry.' Atlantis whispered, running her fingers over the piece of jewelry that was her constant companion since she was a first year at Hogwarts. 'So pathetically sorry.' The vision slipped away from Polaris, and she was dumped on a hard stone floor. A familiar hard stone floor. She was back in Hogwarts, in a small, unused classroom that her friends had commandeered, mostly for fun at first. All the desks and chairs were stacked neatly, with the exception of one desk and one chair. On the desk was a chess set, hewn from quartz and hematite, and beautifully detailed with gold and silver. In the chair sat a young woman with black hair, and black staring eyes surrounded by thick eyelashes. One would have though that she was staring into space, but in reality, the woman was blind, her eyes a milky light blue.
'So it ends.' she whispered to the dark, not knowing that Polaris was there.
'Selene... Please Selene, don't give up...' Polaris said sadly, suddenly afraid. The girl infront of her leaned back and wiped her eyes, making Polaris realize that there were tears coursing down her face.
'There is noting left for us.'
'Selene... don't...'
'Our reign as Gatekeepers is over. It's time.'
"Yes. Time for you to return to your body, my favorite Duani." Kyprioth's soft tenor voice was comforting in her ear. Polaris allowed the god to lead her back, before she slipped into a deep, dreamless sleep.
"Do not fear, my pet, Soon you will have more mischief than you can stand... and more grief to bury." Kyprioth whispered to her, as he left the young woman asleep at her desk; a thousands of miles away from her true home.

This is just the prologue. Polaris and Selene will play major rolls in this story, while the others may fade away. It depends.

Disclaimer: I own all the unfamiliar names (IE- Selene, Polaris, Morgan, Rakuril, and Atlantis) the others are owned by JK Rowling. Kyprioth is the exception (he always has to be... --;;;) as he is owned by Tamora Pierce, part of an excelent set of books called the Tortall books. He appears in Trickster's Choice and Trickster's Queen; and possibly some of the earlier ones I haven't read yet. Oh well.