Bellatrix fears only a few things.
1. Bellatrix fears death. Like all death-eaters, she is terrified of the prospect of dying, and the idea that they will all, someday, die. Ever since she was a young child, and saw her mother die, screaming and choking back blood. She made a resolution that day that she would never die. She didn't know how. She knew that the young, pretty, vulnerable Bellatrix Black would die like all other human beings. That was one of the reasons she created Bellatrix Lestrange. So she could feel immortal. So that she could never die.
2. Bellatrix fears the Dark Lord. Yes, she loves him, but it is not the type of love you get married and have children. It's a passionate, almost fanatical love that people have about things they desire but know they can never have. She's absolutely terrified of him. She loved Tom Riddle, truly loved him. She hates this new, old, bald, ugly, ferocious man that he's become. But she can't stop loving him. She can't stop remembering all the things he promised. She's seen him torture and kill; she's seen him practically bathe in blood and enjoy it. That's what scares her. She tries to be like him. She is his most loyal supporter.
3. Bellatrix fears her father. Yes, he is a frail, disgusting ancient man. But she can't forget the day he first slapped her. It was the first of many, guaranteed, and it was certainly not the hardest or the most painful. She was five, and had "accidently" pushed Narcissa out of her cot. She could still visualise her father storming in, looking around the room, stepping forwards, and slapping her. And when she looked at his face through her tears, she saw only crazy glee. Mental glee. Happiness in the fact his daughter felt pain... She thinks that was the day she went evil.
4. Bellatrix fears herself. Well, no, she doesn't get scared when she looks in the mirror. When she looks in the mirror she just feels sad. She knows she isn't young and innocent anymore. Sometimes, after she's killed someone, she swears that she's covered in blood. That scares her. She knows she's insane. Sometimes she enjoys it; she loves the feeling like she's free as a bird. But then, as her curses hit people, she realises she is not free as a bird. She's trapped inside herself. And when she feels trapped, it is then she starts to feel scared.
Andromeda fears only a few things.
1. Andromeda fears for her family. No, she does not fear for the Blacks. Andromeda knows they are just fine. And even if they weren't, what would she care. She fears for Ted and Dora. They're all she has. If she lost them, she knows she'd probably go as insane as Bellatrix. She left her family, whom she hadloved, all for them. She doesn't want to loose Ted and Dora too. She couldn't take that. Whenever Ted was off treating dangerous inmates, or when Dora was off fighting dark wizards... Andromeda sat at home, wringing her hands.
2. Andromeda is scared of her sisters. As a young child she always felt dominated by her sisters. She loved them, yes, but she wasn't sure what would have happened to her if she hadn't run away with Ted. She had a feeling that Bellatrix would have pushed her out of a window at some point. When she left... She thought Bellatrix was going to cry. That was the only time she saw her sister as vulnerable. Narcissa had been upstairs asleep in bed when she ran away. Narcissa had been 13 years old when Andromeda had run away, always the good girl. Andromeda was scared of Narcissa more. She'd never seen Narcissa cry.
3. Andromeda fears Harry Potter. She isn't sure what he is. She is in awe of him, the boy who lived, but she thinks there is something more to him. Something of... Something of Lord Voldemort in him. She remembered, only a week before, when he'd thought she was Bellatrix. She thought he was going to beat her to death, by the look on his face. She didn't understand him. In truth, he scared her more than Voldemort did.
4. Andromeda feared herself. She didn't trust herself. She felt like Bellatrix. Sometimes, when she was all alone, she wanted to kill herself. Whenever she argued with someone she wanted to use the cruciatus curse on them, to HURT them. She hated and feared the fact that someday, she probably would do something. She feared herself more than she feared for her family, more than she feared her sisters, more than she feared Harry Potter. She was afraid.
Narcissa fears only a few things.
1. Narcissa fears Lord Voldemort. She hates him, because he took her precious son, her precious sister, and her precious husband from her. She fears him because she knows exactly what he'll do to her if he could sense her fear. Thank god Bellatrix had taught her occlumency; otherwise she would have been 5 feet under by now. Narcissa hated that Voldemort had to stay in Malfoy Manor. She feared the fact that Voldemort could kill her in her sleep if he wished. She always charmed her door shut at night when he was staying.
2. Narcissa fears Bellatrix. Narcissa has always feared Bellatrix. She was always in awe of her magnificent big sister as a young child. As she grew older, she recognised how powerful she was... And how evil. Narcissa could remember as young children, Bellatrix used to bully her. As they got older, Bella became extremely protective of her. Narcissa loved Bellatrix. But she also feared her.
3. Narcissa fears the dark. Yes, she knew it was a ridiculous thing for a 40-something year old woman to fear. But whenever she's "asleep" in her room, she has to cuddle into Lucius so she doesn't scream in fear. She used to crawl into Andromeda or Bella's bed when she was little. Usually Andromeda's, because Andromeda was always nicer about being woken up. When Andromeda left, she couldn't do that anymore.
4. Narcissa feared herself. She hated what she'd become: cold, ruthless, cruel, immoral... She wasn't the person she saw in the mirror. She was still little Cissy, right? She smiled to herself bitterly. She was as much "Little Cissy" as Bellatrix was "Little Bella" or Andromeda was "Little Andy". She hated and feared what she'd become. She didn't understand.
The Black Sisters all had their fears. Most were different. However, they were united in one fear. They all feared themselves.