Bellatrix rarely ever cares for anyone, she sees affection and love as a weakness and a waste of time, according to her love is only for the weak. But she does care for her sister Narcissa and a bit for Draco, but mostly for the Dark Lord. So she never really wanted a child of her own since according to her it was a waste of time. And then there was you. You were a friend of Harry Potter's and you were in the Gryffindor house. Every single time there was a plan to get Harry Potter to Voldemort you'd always be there and somehow or the other you'd always foil their plan which was very infuriating for her

You were a thorn in their side and Bellatrix knew she had to get rid of you in order to catch Harry Potter. So what did she do? She decided to stalk you and find out more about you, gathering information so she could get rid of you. She stalked you and watched over you and she didn't know why she felt some warmth inside her heart whenever she watched you smile and laugh. You were a bit of an introvert and kept yourself to yourself, spending your time mostly reading at the courtyard even when it's dark outside. Silly naive girl, don't you know it's dangerous for you to be out like that in the open when there were active Death Eater rallies rising up and Death Eaters causing all sorts of chaos and Dementors running amok as well? She's feeling a bit confused, why the hell would she be concerned with some brat like you? She was supposed to keep tabs on you so she could destroy you and your insufferable Gryffindor pride

It was like she blended with the shadows so well, you won't even notice her keeping tabs on you. She expected you to be picked on some Slytherins because of your docile and gentle nature which she found slightly endearing but when she saw you getting picked on by some twerps and brats from Ravenclaw, she felt mad. Who did these filthy blood traitors think they were, picking on you like that? They dropped your books down and one of them made fun of your stories that you put so much time and effort into. She was wondering where your friends were, the so called Golden Boy of the Wizarding world with the Weasley and the mudblood. When they were done insulting your writing, one of them picked up your book from the floor, read it to the others and laughed out "I can't believe you waste your time writing garbage like this. Even an ogre has better creativity than you'' and you felt tears pricked your eyes but you quickly blinked them away. You didn't want to be sees as a crybaby of some sort

After they were done making fun of you, to add an insult to injury someone said "Freaks like you don't belong at Hogwarts'' and just as they were about to hex you, Bellatrix felt like she had to do something to at least prevent you from getting hexed. But before she could do so you gritted your teeth as you pulled out your wand and hexed them all. You sent them running away in fear and Bellatrix grinned to herself when they ran off like cowards, she felt some pride inside her. You picked up your stuff and you got to Potions class. Snape gave you detention of sorting out fresh and rotten flobberworms since you were 10 minutes late and Bellatrix gritted her teeth. She decided to have a word with him later on, why was he making such a big deal just because you were late? She never really liked him anyways. Besides, you were being picked on

Bellatrix would deal with those annoying pests later on. She'd bring them to some secluded spot and end up killing them. Pretty soon she accepts that she does care for you, when she sees you look sad she feels a bit bad and just wants to ask you what's wrong and eradicate the source of your unhappiness. She knows the people at Hogwarts are completely incompetent when it comes to protecting students and her protective instincts told her that you wouldn't be safer there. So she did the next logical thing and decided to kidnap you. By now she didn't care if you were a pure blood or not, she liked you, she'd have you. That's it. When she wants something she'll take it without a second thought. When you wake up on a bed and when you see her, of course you'll be screaming your head off. You literally just go freaking kidnapped by one of the most feared and dangerous Death Eaters

"Oh for Merlin's sake, calm down would you, I'm not going to kill you. Yet'' she said which of course made you fearful even more. She just scoffed and told you there were clothes for you to change into and there was something to eat for you. You were confused as hell, why did she kidnap you and why was she being nice to you like this? "I need to go back to my parents, it's going to be the holidays soon'' you said after 2 days. She refused and when you tried to escape by using a wand you found in one of the drawers there, she cast a spell that split the wand into two and you were now tied to your bed. Don't be too surprised if your parents end up missing or being killed by her and a bunch of other Death Eaters. You're the very first person she's actually ever cared about with all her heart and she has no intention of letting you go, ever