Author's Notes:

So this is a Captain Swan angel/demon AU. Various other OUAT characters will also be worked into this in various ways. It's certainly Catholic-inspired, but with various liberties taken for the sake of the story. If you like it, reviews would be grand, if you don't, no harm, no foul. It's going to be different from some of the other stuff I've written - but I like the idea and hope some of you will too! Mature content.

This will primarily be set in the present day, but the prologue takes place in the past and there will be some flashback scenes throughout the fic as well.

Any Latin words are from Google Translate - apologies for any errors, I'm just going with a literal word-to-word translation.

Between Heaven and Hell

Prologue

"Remember tonight, for it is the beginning of always"

Dante Alighieri

Rome - May 6, 1527

God has forsaken us.

The thought came unbidden to her panicked mind and the horror of the realization overwhelmed her. It was true, there was no other explanation for how the holy city could have fallen to the Emperor's troops, barbarous men who had scaled the walls and broken down the gates and were now running rampant in the streets, indulging in a violent orgy of mass destruction and deranged debauchery, the likes of which had never been seen in living memory.

They dragged men of the cloth from the pulpits and stripped them naked on the steps of their churches, whipping them to ribbons and staining the stone with rivers of blood. The convents were ransacked, the brides of Christ degraded and violated in their cells and their throats slit, pleas for mercy falling on deaf ears, prayers unanswered. The city was burning, none were spared, from babes in arms to the elderly and infirm, from prostitutes to priests, beggars to nobles. It was wholesale slaughter on an unprecedented scale, as the devil took hold in the form of the bloodthirsty soldiers and the angels fled. Even His Holiness was gone, spirited away under cover of night while his loyal Swiss Guard was massacred under the great stone shadow of St. Peter's dome.

The last defenders of Rome were gone, God had abandoned them as surely as the Medici pope, Clement VII, to meet their fate.

Sister Maria Anna fingered the rosary beads hanging at her waist. There was no comfort now in the familiar ritual of the Pater Noster prayer, God was no longer listening to His children trapped in His city. She let the beads fall back down and huddled closer to her three companions, the only ones left of their order. They had been lucky, managing to find hiding spaces in the abbey when the soldiers broke down the barricaded door and dragged the others off. The four of them had spent agonizing hours in their cramped refuge, expecting the soldiers to return and find them at any moment, before they escaped unseen when the night finally fell. Maria Anna had grown up in the city, unlike most of her sisters, and knew well the back alleys and hidden lanes that wound like a giant maze around the open squares where the worst of the rioting and carnage was taking place. Their dark habits blended into the shadows, the starched white wimples discarded lest they draw any light from the soldiers' torches and lanterns. But the night wouldn't last forever, and just as she despaired of finding any hope of sanctuary in the fallen city, Sister Maria Katherina grasped her arm and pointed with a hissed, "Look!"

A single candle in a fogged window, a beacon, and a woman behind it, beckoning to the frightened nuns with a smile that somehow eased Maria Anna's frantically beating heart.

The woman led them into the silent house, to a room at the rear of the long and narrow abode as far from the street as possible and doused the candle. Before the tiny light winked out Maria Anna had seen a rich gold satin dress, a heavy fall of unbound wheaten hair and green eyes in a white face, with a serenity that was woefully out of place in the depths of the hell to which they had all descended. But somehow, under the woman's guiding hand she felt the tiniest flicker of hope, and her fingers found the jet beads and the silver cross once more. Perhaps her prayer had not gone unheard after all.

Mingled shouts and cries came from outside, carrying through the thin walls. Maria Theresa had her head buried in Maria Anna's shoulder and her whole body shook with fear, the young novitiate was just eleven and had witnessed atrocities no child should see.

There was a rustle of satin and the woman's voice whispered, "You will be safe here, I will see to it."

Her hand found Maria Anna's and gave a reassuring squeeze. There was a brief tingle in her palm at the woman's touch and she felt a warm breeze brush against her cold cheek, reminding her of days when the sun shone through the leaded panes of stained glass in the abbey. The soldiers had broken the windows, the shards of red and blue and yellow scattering across the floor and ground to dust under their boots.

The sound of creaking wood and heavy footfalls from elsewhere in the house, so like a soldier's arrogant stride, made her breath catch in her throat. Maria Theresa cried out and Maria Anna clapped a hand over her mouth but the damage was done. The steps came closer and the door to the small room was pushed open, a light appearing from the other side. It came from a lantern, held aloft by a man dressed all in black, with hair like a raven's wing and eyes as blue as the Virgin's cloak. But there was no warmth in his gaze, his smile was that of a wolf who had spotted weak prey, and Maria Anna pressed back against the wall behind her.

"Well," the man spoke in a voice that was low and laced with amusement, "What a surprise. It seems that not all of the blessed ones have fled."

The soft yellow light swung across the woman and illuminated the serene smile that did not waver in the face of the threatening figure. She responded in an equally low voice, but her conviction rang clear in each word, "You can't touch them. Their souls are innocent."

He looked over the woman's shoulder and his eyes met Maria Anna's. She flinched back, feeling something cold prod against her skin, a sudden sharp chill that swept over her and made her feel like she had been fully stipped bare and every inch examined head to toe in that brief look. Maria Theresa sagged against her, the girl had fainted right away.

Lips curled back over white teeth and his tongue ran across them, "I can't, but there's plenty out there who can. There will be no innocent souls left in Rome when the army is through, they've lost all reason and the depravity is shocking, even by my standards."

God save us, she prayed silently in her head while her knees threatened to give out and only Maria Theresa's weight against her was still keeping her upright.

The woman took a step forward, she was clearly unafraid of the dark haired man even as Maria Anna desperately fought the urge to flee from his dark voice and piercing gaze.

"Is that why you're here?" the woman asked, "Seeking out these few who've managed to escape the spread of evil?"

His eyes found them again briefly and she shuddered while she sought out the rosary beads with her free hand and rolled them in her fingers.

Deliver us from evil.

"No," the man answered, looking back at the woman's face again, "It's not them that drew me here, it's you. The city has gone dark tonight but your light still shines. I was curious as to who could have stayed behind."

Silence reigned for a long moment, the light from the lantern flickering over them and throwing strange shadows on the walls. The man and the woman stared at each other, seemingly locked in an unspoken battle of wills.

He was the one who seemed to concede, stepping back with a shake of his head, "You should leave now, blessed one. Rome has fallen and you know what will be coming to revel in the defilement of the holy. Your light will call out to them as it did to me. Save yourself while you still have the chance."

The woman turned and drew her gaze slowly over Maria Anna and the others. A sad smile lifted her lips, "No. They are innocent and I have sworn to protect them. I can't leave them."

Maria Anna found her voice at last, "If you can escape the city, dear lady, you must go. Worry not for us."

Maria Katherina was reciting a desperate prayer with her eyes closed and her crucifix clutched in her hands, Maria Johanna was frozen in place, her eyes wide and terrified, and Maria Theresa had roused from her faint and was sobbing quietly, face still buried in Maria Anna's shoulder.

"How appallingly noble," the man scoffed, "You have no idea what's coming for you, Sister."

His face was handsome but hard, as if it had been carved from marble. There was something about the man that she couldn't quite place, he didn't have the look of a native Roman, nor that of the Emperor's Germanic troops. He was not garbed as a cleric, was obviously not a peasant, his bearing was proud and noble but he was like no lord she had ever seen. Maria Anna felt both repulsed and intrigued, her mind swirling with sudden images of being laid out naked underneath him and forswearing her vows, giving in to every forbidden carnal urge and fornicating madly until her soul was damned to the eternal fires.

She wrenched her eyes away from his with a gasp, frantically pushing the thoughts away and clutching her silver cross so hard it bit deeply into her palm. Maria Anna heard a dark chuckle and she could feel his gaze still on her.

"Innocence never lasts," he said, "Why risk yourself on a futile endeavour?"

"It's not something I'd expect you to understand," the woman replied tartly, "Come, Sisters, we must find a way out of the city."

"There's only one way out now. You wouldn't last five minutes on the streets at this point. If you insist on this foolishness and refuse to ascend, then you must head down below. Follow me, I will guide you out of Rome."

The woman turned back to him with a swirl of her satin skirts and she sounded as incredulous as Maria Anna felt, "Follow you? You are going to assist my futile endeavour? Why should I possibly believe that?"

He moved in the blink of an eye, standing toe to toe with the woman and staring down at her. Maria Anna's heart beat painfully in her chest, she was chilled to the bone with fear and she wanted to snatch the woman back and pull her away from the man who loomed over her, a dark spectre who seemed to fill the room and somehow terrified her more than the thought of the Emperor's entire army surrounding the house. But she couldn't move, she was rooted right to the spot.

"You really shouldn't, but what do you have to lose, blessed one?" he asked with a grin.

The old catacombs that wormed their way under the city like veins of quartz in rock were silent save for the footsteps of the strange group. The man led the way, the light from his lantern flickering on the soft brown bones of ancient martyrs and saints, the empty dark hollows that had once been eyes watching from the niches in the walls that were their final resting place. She said a prayer for their immortal souls and begged their forgiveness for disturbing their eternal rest. The four nuns had all joined hands lest one falter, shuffling forward on the uneven jumble of stone and earth under their feet.

The woman walked just behind the man with unerring steps, her back straight and her head high. Whenever Maria Anna's despair threatened to overwhelm her, fearing that they would never find their way out of the underground tombs, the woman seemed to sense her fear and would turn her head and smile reassuringly,

"Just a little farther," she whispered.

Maria Anna didn't even know the woman's name, there had been no time to ask, but she gave a prayer of thanks in her head for her assistance and steady, calming presence.

She couldn't bring herself to add the man to her prayer, even as he found tiny passageways that were nearly hidden in the gloom and connected the various chambers. Some were so narrow they had to be traversed sideways, creeping through one by one with the stale air burning their lungs and leaving a rancid taste in the back of their throats. Every time it seemed they could go no farther, the man would find a way to press on, his long ringed fingers probing the walls and pointing the way. Maria Anna had no idea why he was helping them or why the woman had accepted his assistance, or even why she and her sisters were following them both.

"He is leading us straight into infernum," Maria Johanna muttered at one point, "Right to the gates to deliver is to the devil himself."

The man must have heard her, he laughed and the lantern swung around, "Welcome to infernum, Sister."

Maria Johanna flinched, her mouth set in a thin line when his eyes landed on her and the nuns all froze as one.

"Shall I lead you there? Are you perhaps curious as to whether or not the descriptions in your holy scriptures are true? Do you wish to touch the eternal fire and see if really burns? All you have to do is say the word."

The images flashed behind Maria Anna's lids, of writhing with ecstasy in the flames with his hands on her flesh, tearing it right from her bones and devouring her whole.

"This one is considering it."

She opened her eyes and he was looking right at her with a cold and devious smile. Her fingers groped for her rosary and found only empty air.

"Stop. It."

The woman stepped in front of Maria Anna and blocked her view of the man.

He sounded amused, "Do you still think they're worth the risk?"

"If I didn't, would I still be here?"

Where could she go? Maria Anna wondered. There was no turning back now, nowhere to go except to follow the man, wherever he was leading them. Salvation or damnation, the light from the woman's candle or the darkness in the man's eyes. He reached out as if to touch the woman's face, but paused and only flicked a strand of her hair back over her shoulder.

"What about you, blessed one? Do you think I'm leading you all astray, my little lambs to the slaughter?"

The woman shook her head, "No. You could, but I don't think you are, infernal one."

He sucked in a whistling breath between his teeth, "Interesting. One of your kind trusting me. On what basis did I manage to earn your trust?"

"You didn't. I don't trust you, but I have faith."

The man laughed, "An unshakable faith, I see. Well, come along then, we're almost there. I am not taking you to hell, dear Sisters, I shall guide you back to the path to caelo, though you will excuse me if I go no farther than that."

He pressed on, kicking aside the bones that were scattered across the floor with careless disregard. Maria Anna couldn't move, she could scarcely think, there was nothing in her head excerpt that terrible graven image that he had put there. Would the flames burn her? She almost wanted to know.

"Sister."

The woman's white face loomed in front of her out of the dark, she grasped Maria Anna's hands and the rosary, pressing the cross into her palm. As it had before, the woman's touch seemed to impart a strength, a sense of calm and peace even in the tiny cavern of crumbling bones deep underneath the earth.

"You do not wish to go down that path, Sister. Follow him, but do not look into his eyes."

"What is he?" Maria Anna whispered, "What are you?"

The woman didn't answer directly, she just smiled and said, "Someone who heard a prayer."

When they finally emerged into the faint dawning light of the sunrise, outside the city walls, the four nuns all took in great gasping breaths, eager to rid their lungs of the dust and decay from their long trek through the hidden realm of the dead. They had come up through the undercroft of an old chapel that was now a near ruin, only two stone walls still standing. Green shoots rose from between the broken stone slabs that had once made up the floor, the man hefted back the one he had shoved aside with the woman's assistance, covering up the narrow steps they had just climbed.

"Come, we can't tarry here. We must get as far away from Rome as possible," the woman urged, pulling the exhausted nuns back to their feet.

"Head south," the man advised. Maria Anna was careful to keep her gaze lowered and avoided looking at his face. She saw the woman's skirt move, the heavy folds of gold satin sweeping across the weathered stones where the worshippers had once knelt to pray.

"Why?" she asked, "A veritable feast for you in the city last night and you turned it away and brought four innocents to safety. A strange action to say the least, infernal one."

His voice was low but Maria Anna could still hear each word, "Oh, I didn't do it for them, blessed one. Now, in return for my generous assistance, I have one simple request. Tell me your name."

She chanced a glance up and saw surprise on the woman's face, the first time her serenity had faltered and faded.

"I shall tell you mine," he encouraged when she remained silent.

"Emma."

She said it with some reluctance, taking a step back from him.

"Emma," the man repeated, and something in his voice made Maria Anna shiver. He spoke the name as a caress, a whisper, a promise and gave a courtly bow, bending low at the waist with a sweep of his short cloak.

"My name is Killian. Remember that, for I think we shall meet again one day. But I shall take my leave of you now. The delights of Rome still await, I may have missed out on some of the fun but there is plenty of amusement left. The army won't be satisfied with one night, it shall continue for weeks if not months and they may wind up burning the holy city right to the ground."

"And you will be there to stoke the flames."

"We all serve our purpose. Farewell, Emma. The light that did not flee the darkness. It was truly a pleasure."

He drew the word "pleasure" out obscenely, and then he was gone.

The other three started towards the road that led away from the city, but Maria Anna stayed behind and grabbed Emma's sleeve.

"What was he?" she asked again, fearing the answer.

Emma's voice was clipped, "A corrupter. One who can take your soul and twist it into something very dark, if you let him. Do not think of him after this day and never ever speak his name."

Maria Anna blinked, "What are you?"

The gentle smile returned, "Dear Isabella, you know what I am."

The use of her long disused birth name stunned Maria Anna into silence.

They left Rome behind. The pillage continued for months on end as the Emperor's troops occupied the city and thousands upon thousands died. The Pope was humiliated and forced to grovel for mercy under the Emperor's boot, paying ransom and ceding lands and territories to the Hapsburg king.

And for the rest of her life Maria Anna lit a candle every day and said a prayer of thanks for the angel who had appeared when the city fell and saved her and her three sisters, for she knew now that was what the woman was.

"Gratia, tibi beata angela, Emma." "Thank you, blessed angel, Emma."

As for the dark haired demon who had also appeared and helped lead them from the city that night, she heeded the angel's warning. He had tempted her soul once but she would not give him the chance to lead her into sin and damnation again.

Maria Anna could not truly forget him, but she never spoke his name.