A/N: JKR owns the characters, I'm simply borrowing them. This was written for the HP Potions Comp: Hate potion. Enjoy!

Bellatrix always hated her cousin, Sirius. She had hated him from the moment he had come into the world.

Her parents were going on and on about precious baby Sirius, and how excited her Uncle Orion and Aunt Walburga were to finally have a baby.

But she thought he was a brat. The moment he put his chubby little hand into her curls, tugging on them furiously, she had hated him.

And it didn't get better with time. The older Sirius became, the more people seemed to fall in love with him. Well, everyone but her. She saw the mischievous glint in his eye and knew it meant nothing but trouble. He was too blunt to be a Slytherin. He wouldn't make their family proud, she just knew it.

All she ever heard about was Sirius's first steps, first words, first case of accidental magic… the list went on and on.

It was infuriating.

And when she went to Hogwarts, Bellatrix thought she'd finally be away from the little brat. But still, he seemed to haunt her.

Sirius Black would pop up in her dreams, tormenting her on no end. Her mother would gush about in her letters, and Narcissa would always write about what little Sirius did today.

Honestly, it made Bella want to vomit.

The years passed, and soon Sirius Black attended Hogwarts, becoming sorted into Gryffindor. He made friends with Potter, who was another Pureblood… but one that wasn't one the right side.

Bella heard her father talking… she knew all about Pureblood history and how she was better than all the Half-Bloods and Mudbloods at the school.

But Sirius paid no difference to blood status, becoming friends with anyone and that drove Bellatrix crazy. Didn't he know any better? Didn't he care about the disgrace he was giving their family?

She had pegged him as a blood traitor from the start.

Her hatred for her cousin grew even more when he ran away from home. He showed no respect to his parents, simply leaving to be with those Potters. Aunt Walburga said she was so disappointed in her son and that only fueled the hatred Bella felt.

The next time she knew she absolutely loathed Sirius Black was when she met him in Battle one day.

The Dark Lord had sent them out to raid the McKinnon home, but when they had arrived, Dumbledore's precious Order was already there.

The two of them had dueled, curses going every which way. Sirius was only aiming to hurt, while she was aiming to kill.

So when the opportunity presented itself, Bellatrix casted the Killing Curse, killing Marlene McKinnon, Sirius' fiancé.

His tortured scream filled the air, causing her to grin wildly. The bloodlust filled her senses, causing her to see red. Bella lunged forward, ready to kill her cousin and finish the job, but he Apparated away like a blood coward.

But she would get him. She would strike him down.

Her Master was gone now, but Bella knew he would return. So she waited, biding her time in Azkaban. She didn't really mind though, seeing as Sirius was only a few cells down.

She screamed and shouted, often speaking of how wonderful killing Marlene was and how brilliant it was that the Potters had been killed. She knew his words hurt him… which was why she continued to do it.

All she could do now was torture Sirius verbally. She hated him, but knew that when her Master returned, she'd be able to get him.

There'd be no stains on their family tree.

A frustrated scream came from her lips, snapping her out of her thoughts. She couldn't believe what the guard was saying… she wouldn't. She heard the murmurs, the rumors… but they just couldn't be true… could they?

Did her stupid cousin actually break out of Azkaban?

She screamed once more.

"Potter is saying You-Know-Who has returned."

Bella's head snapped up, a wild grin appearing on her face. "Is it true?" she asked, rushing over to the bars of her cell. She smiled sadistically as they stumbled back a few steps.

"None of your business, prisoner," one of the guards spat at her.

Bellatrix laughed. "It is, isn't it? Just you wait, he'll come for me," she cried out, before falling back into the shadows. "He'll come for me, and then I'll kill Sirius."

And she was right. He came for her, freeing her from the prisoner. And He rewarded her loyalty.

So with her head held high, Bella Apparated to the Ministry with Lucius, eager to get the Prophecy.

Potter and the other brats put up a fight, but it was a rather pitiful one. Just as Potter finally handed over the Prophecy, the Order appeared. Sirius was with them.

Bella wasted no time, turning into her smoke form and rushing throughout the room. She attacked Order members, the fight turning her more and more crazed. This was what she lived for!

She landed the moment Lucius was disarmed, and without hesitation, Bella raised her wand, screaming "Avada Kedavra!"

She watched in glee as the green light sped forward, crashing into Sirius' chest. His body tumbled backwards, falling into the Veil.

She had done it! Sirius was dead, and by her hand, and he would no more pollute their family.

Aunt Walburga's words flickered through her mind at that moment. "Every family has a bad seed, but it's important to crush that seed before it can grow and spread." Bella had done just that.

So as she ran into the foyer, Potter following her, she couldn't help but scream in happiness. She had done it.

"I killed Sirius Black!" she shouted hysterically, turning to taught Potter.

She had done it.