Note: in this fic I have disregarded the fact that Bellatrix and Sirius are cousins. Repeat, no incest intended! They are not related!

Disclaimer: Harry Potter not mine. Enjoy!

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How was I to know that I would be the one to kill him?

That night…that night at the Ministry…it was all a mistake. Potter was supposed to die. I would have killed him with my bare hands, wrapped them around his wretched, scrawny throat… but I don't regret what I did.

He was the only man who ever loved me. And I? Well…I was always happy to return to him. There will only ever be one man that I love. And he chose me… the Dark Lord chose me.

What could I have done? He wanted me. So I killed him. I killed Sirius Black.

15 years earlier…

Sirius sighed. He took a large, surly sip of his beer as he sat in the corner of a small, dark muggle pub. He stared moodily at the table before him, lost in thought as he was always prone to do in this place. It was his retreat from the wizarding world - from his friends, from his many female admirers, from his family, from magic altogether.

His day had been shocking. Following an anonymous tip off, the Order had raided a manor in the south of England in hopes of finding Voldemort's latest hide out. But once they arrived it was obvious that it had been a trap as a dozen Death Eaters pounced from the shadows, attacking to kill.

By some miracle Remus, Moody, Hagrid, Frank and Alice Longbottom and Sirius had all managed to make it out alive, but only just. Moody's leg had almost been cursed off and Sirius had the nasty suspicion that he would never walk normally again, while Alice had collapsed as an unknown jinx hit her. It was only upon returning to the Order that it was revealed that Alice was two months pregnant at the time and Frank was in a state of panic, unable to be calmed, as he feared for the life of his unborn child.

It had been Bellatrix Lestrange that had cursed her. Sirius could feel his blood boiling at the thought of her - he doubted whether a more evil witch had ever existed.

Suddenly, the door to the pub creaked open and Sirius choked on his beer. It was her. Bellatrix Lestrange.

She took a seat at the bar without seeing him and ordered a drink. Sirius' hand was itching to reach for his wand and kill her on the spot - but there were too many witnesses. He would follow her when she left.

He watched her from his shadowy corner for half an hour and saw as she dismissed man after man who approached her hopefully. She appeared to be incredibly pissed off, even more so than usual, judging by the way she was glaring at the wall in front of her.

Finally, she got up to leave and Sirius hastened after her. He followed from a distance as she walked hastily down the street and turned into a dark alley. Sirius quickened his pace, not wanting to miss her before she Disapparated. He burst into the alleyway at a sprint and then-

'Crucify!'

Sirius just dodged her curse as he rolled behind a dumpster. Bellatrix laughed.

'Stupid fool, did you think I didn't notice you following me?' she hissed coldly, approaching him with her wand out. Sirius drew his own and clutched it tightly, waiting to make his move.

'No, I thought you'd be too drunk to notice.'

Sirius jumped up and aimed a stunning spell at her, which she deflected easily.

'I saw you knocking back the vodkas back there-'

Bellatrix hissed angrily and Sirius ducked to avoid her curse.

'What's wrong?' he asked casually, as if talking to an old friend. 'Voldemort found another whore for the night?'

Bellatrix howled in rage and, forgetting her wand, flew at him. Sirius was taken by surprise and doubled over as she punched him in the stomach. Bellatrix was coming back for a second attack, but Sirius caught her arm easily and pushed her away.

'How dare you,' she screeched, still trying to get at him. Sirius laughed.

'Touched a nerve, did I?'

Bellatrix wrenched her arm from his grasp and caught him on the chin with her fist as her foot collided with his shin. Sirius staggered.

'You little-'

He started forwards and, without pausing to consider that she was a woman only half his size, swung a fist fully into her face. Immediately Bellatrix fell to the ground, out cold.

Sirius stared at her in shock. He hadn't meant to hit her…at least not that hard.

He glanced around and was relieved to see the street was deserted. He looked down at her again and hesitated.

Killing her now seemed wrong, too wrong. He settled instead for taking her wand and was in the process of conjuring ropes to tie her hands when she stirred. Jumping to her feet with incredibly speed for someone who had only moments ago been unconscious, Bellatrix looked around for him and felt for her wand.

'Where's my-' she stopped as she saw Sirius twirling it between his fingers. For some reason she smiled.

'Going to kill me, Black?' she sneered, stepping towards him confidently.

'Why, yes, I am quite seriously considering it,' Sirius replied coolly, walking backwards to keep her at a safe distance.

'Aw, does little Blacky want revenge for his friend's leg?' she cooed mockingly, still walking towards him. Sirius was now backed against the alleyway's wall, with nowhere to go. He held the two wands out in front of him and Bellatrix stopped, eyeing them menacingly. She was breathing steadily, and Sirius couldn't help watching her chest as it rose and fell heavily. This didn't go by unnoticed.

'Like what you see?' Bellatrix asked him coldly. Sirius grinned.

'I can do without Voldemort's sloppy seconds, thanks.'

Bellatrix went red with fury and stepped towards him again.

'How dare you say his name?' she whispered. Sirius lowered his wands and took a step towards her so that he towered over her. Their faces were inches apart.

'Vol-de-mort,' he said clearly. Bellatrix hissed with rage, and Sirius was caught up in watching her lips as her tongue darted out to moisten them. Bellatrix noticed this, too, and was suddenly very aware of Sirius' impressively large frame, and how close he was standing to her.

How could such an idiot be gifted with such good looks, she thought furiously, taking in his dark, messy hair and his glittering eyes. Sirius raised his eyebrows at her and she blushed ever so slightly.

'Get away from me, Black.'

Instead, Sirius stepped towards her again. She felt his strong chest pressing against her own, and knew he must be able to feel her nipples, which had suddenly become very hard, through her shirt.

'But you don't want me to...' Sirius said in his very deep voice.

Neither knew who did it first. But next thing they knew, they were kissing fiercely, their wands rolling away across the ground as they ripped at each other's clothing.

Sirius picked her up and Bellatrix wrapped her legs around his waist as he threw her against the wall with no concern whatsoever as she let out a yelp of pain. With a kind of unspoken ferocity Sirius pushed her skirt out of the way as she unzipped his pants and pulled him free.

Both of them bit down on their tongues as he entered her, determined not to give each other the satisfaction of knowing how good it felt. They moved urgently and silently, the only sound that of Bellatrix's back as it was repeatedly slammed against the hard, cold wall.

Soon she could no longer contain a small gasp of pleasure as she reached her peak and at the feeling of her insides gripping him tightly Sirius became rigid, emptying himself deep inside her.

As their movements slowly ceased, Bellatrix pushed him away roughly and Sirius let her drop to the ground where she nearly fell, her knees weak. They were both panting heavily as they quickly dressed and searched for their wands. They spotted them at the same time and reached, each grabbing the other's in a rush.

They pointed them before them, each eyeing the other silently. Then, they both quickly flung out their hands and snatched their wands from each other, before Disapparating without another word.

--

It was two weeks later and Voldemort had been making some recent progress after hearing a strange prophecy about himself and an unborn child. Without realising that he hadn't heard the whole story, Voldemort sent out his Death Eaters to find anyone who had ever escaped from him with orders to kill on sight.

Bellatrix had been searching ever since, hoping to come across a certain male in her travels (although she would never admit this to herself). So far she had been unsuccessful, although she had killed two aurors, much to her satisfaction.

She had returned twice to the small muggle pub, but she hadn't seen Sirius once. Afterwards she had punished herself, furious that she couldn't get him out of her head, while another part of her was just as angry at him for not looking for her.

'Bella!' Voldemort called her into his chamber. She bowed low as she entered and kissed his hand.

'My Lord?'

'Word has reached me…about the Potters…' Bellatrix dared to glance up at him.

'The Potters, my Lord?'

'They have thrice defied me, as the prophecy said. I have a feeling, Bella…' he trailed off, his eyes glinting hungrily.

'What do you wish me to do, my Lord?'

'Find them. Now.' Bellatrix stood immediately.

'Yes, my Lord. I will find them for you.'

'Remember, Bella. You are my most faithful…you will be greatly rewarded.'

Bellatrix quivered with excitement. Maybe he would finally take her. She had dreamed about it since the day she had entered his service. Her marriage to Rodolphus meant nothing, even on her wedding night she had thought of no one but the Dark Lord. Frankly, she was pleased that Voldemort had sent him overseas for some kind of goblin negotiation.

'I'll leave right now, my Lord.'

--

Bellatrix apparated to a small muggle village south of London where she had heard rumours the Potters had been seen. Muttering a few well-chosen words, Bellatrix waved her wand and immediately a faint white glow appeared around her, trailing out of sight straight ahead.

She followed the glow, which traced recent magic activity, until she reached a tiny cottage. Performing a disillusionment charm upon herself, Bellatrix crept quietly around the side of the house and slid in the back door.

Immediately, a deafening alarm sounded and she heard broken glass up ahead.

Lily Potter came skidding out of the kitchen, her wand raised and ready. Bellatrix couldn't help but notice that she was…larger than normal.

'Expelliarmus!' she cried, but Bellatrix had ducked behind the door. 'James! Death Eaters!' Lily screamed, and thunderous footsteps told Bellatrix that she was about to be outnumbered. This meant nothing to her - she had bested four wizards at once before, killing them all.

But she was not prepared for what happened next. James Potter came running down the stairs and shielded his wife. He raised his wand, but Bellatrix was ready for him, when-

Someone suddenly dropped right in front of Bellatrix from nowhere - Sirius Black had jumped over the banister from the second floor and landed with a clumsy elegance barely a metre from her, his wand pointed right at her chest.

For a moment they stared at each other, frozen. Suddenly, Sirius gave a booming yell.

'James, Lily - go!'

'Not without y-'

'I'll be fine, now go!'

Lily and James ran for the door and Disapparated without a backwards glance. Sirius glanced over his shoulder to check they were gone, then smirked.

'I thought you would come.'

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First chapter! It's about to get a lot more interesting...Please let me know what you think!