Narcissa/Bellatrix x OC

Everyone finds out about Ellie and Bellatrix (but not Narcissa and Ellie)

Ellie sits in the library of Malfoy Manor, reading a dark arts book. A hand grabs her hair forces her to look straight up. "Hello there." Ellie says.
"What are you reading?" Bellatrix asks.
"Dark Arts book. Trying to find new ways to scare the Carrows."
"You really enjoy terrorizing them don't you?" Bellatrix pushes Ellie's head back before walking around the couch and sitting next to Ellie.
"Well since the Dark Lord and my father are forcing me to go to Hogwarts I might as well have some fun." Bellatrix puts an arm around Ellie's shoulders
"Does the Dark Lord know you're terrorizing two of his best Death Eaters?"
"Where do you think I got this book from? He says it keeps them on their toes. Do you need something or do you just want to be near me?"
"Shut up." Ellie chuckles before returning to her reading. After a minute, Bellatrix starts playing with Ellie's hair. Ellie carefully and slowly lifts her legs onto the couch and leans against Bellatrix. Bellatrix tenses for a moment before relaxing. Ellie lays her head on Bellatrix's shoulder and Bellatrix gently kisses the top of her head. Bellatrix whispers so quietly Ellie almost doesn't hear it. "Mine." Ellie smiles softly to herself. They stay this way, Bellatrix half reading Ellie's book too, for a while.
     "What the hell am I looking at?" Draco questions when he silently opens the door.
     "Shit." Bellatrix shoots up and Ellie falls onto the couch. Bellatrix takes a few steps away from Ellie
     "Bitch." Ellie mumbles.
     "Yeah this explains a lot." Draco says. "Especially part of your Amortentia last year."
     "Hi Draco, what's up?" Ellie says. Ellie sees Bellatrix draw her wand and Ellie disarms her before she can do anything. "You are not using the Memory Charm on Draco. Narcissa would kill you."
     "Little brat." Bellatrix says.
     "It's been a year. Someone was bound to find out eventually."
     "So... you two." Draco says.
     "Yeah."
     "Does Uncle know this?"
     "He doesn't know it's her." Bellatrix answers.
     "I assume Snape doesn't know."
     "He doesn't but he's getting suspicious." Ellie says.
     "Am I the only one who knows?"
     "No, your mother knows."
     "What is taking so long Draco?" Narcissa says as she walks in. She looks around the room and immediately knows what happened. "Did he catch you?"
     "Little bit. Don't worry, it wasn't anything bad."
     "I told you two that you were going to get caught eventually. Come Draco." Draco grabs the book he came for and follows Narcissa
     "What was he talking about with Amortentia?" Bellatrix asks.
     "Slughorn had everyone smell it last year." Ellie replies.
     "and?"
     "And the part Draco was talking about smelt like smoke and other elements of fire and the metallic smell of fresh blood."
     "Sound about right for me. What was the rest?"
     "Cissa, expensive perfume and fresh mint. So... half the manor knows. Should we just tell everyone?"
     "I'll think about it, but for now." Bellatrix walks up to Ellie and grabs her by her shirt. "You know better than to disarm me."
     The next day, Bellatrix calls a house meeting. "What is this meeting for?" Draco asks as he and Ellie walk down the hall to the sitting room.
     "Telling everyone else about our relationship."
     "Who or what did the rest of your Amortentia smell like?"
     "Let's leave it at, if I told you, you would be traumatized. Why do you ask?"
     "Because it sounded like my mother." Ellie winks and smirks at Draco. "Ewww really?"
     "Yes really. It ended when your father got back. Now its just Bella, well for the most part." Draco stares emotionlessly at the hall in front of them. "I told you it would traumatize you. Don't tell your father. He just knows there was another person."
     They get to the sitting room to find everyone there. "Why is she here?" Lucius asks. "I thought this was a family meeting."
     "It's a house meeting." Ellie says.
     "Which explains the Dark Lord's presence but not yours."
     "I'm here every weekend."
     "Don't remind me."
     "Enough!" Bellatrix snaps.
     "Sorry." Ellie says.
     "Does this have anything to do with whatever you two have been hiding?" Voldemort asks.
     "Yes, my Lord." Bellatrix replies.
     "That you two are together?" Rodolphus asks.
     "What?" Lucius questions.
     "How did you know?" Ellie asks.
     "You two aren't as subtle as you seem to think you are, dear." Narcissa says.
     "Clearly Lucius didn't know." Ellie replies.
     "Well I tend to ignore your presence." Lucius says. Bellatrix glares at Lucius.
     "Oh she's going to be protective and possessive now, isn't she?" Ellie asks.
     "Very." Narcissa replies.
     "Just don't make me regret letting either of you stay here." Lucius says.
     "You don't have a choice with me. I'm here on the Dark Lord's orders." Ellie says with a smirk.
     "My house, my rule." Lucius says.
     "My knife, your life." Ellie replies.
     "That's my girl." Bellatrix says.
     When Ellie returns to Hogwarts, Snape walks up to her. "You and I need to have a talk." He says.
     "Okay?" Ellie questions before following him to his office. "What's going on?"
     "I don't know, you tell me. Why has Bellatrix been here three times in the last week?"
     "How should I know?"
     "Elliandria stop playing dumb. I know she is with you when she's here. Is this why you wanted private quarters and why you go Malfoy Manor every weekend?"
     "No. I was really getting tired of the other girls. As for the Manor, the Dark Lord still doesn't trust me completely and wants to keep an eye on me. He trusts you to keep an eye on me during the week."
     "Why Bellatrix?"
     "No idea why. Just happened."
     "How long has this been going on?"
     "Pretty much since I got my Apparition License."
     "How did I not know this?"
     "I usually snuck my necklace into a friend's bag and summoned it to me when I got back to Hogsmeade."
     "So the time I went to Malfoy Manor to update Narcissa about Draco and saw your jacket?"
     "I wore the jacket there and slid the necklace into the pocket once I realized I still had it on."
     "Who else knows?"
     "Her family... and her husband... and the Dark Lord. Basically anyone who lives in the manor."
     "How did this happen in the first place?"
     "The second time I was kidnapped, Narcissa and Bellatrix left a note in my textbook. They wanted to talk to me about something. It evolved from there."
     "Wait, Narcissa was involved?"
     "Yeah but that basically ended when Lucius came back and I started getting attached to Bella."
     "I want to keep you away from her, but I know you're an adult. Just please be careful."
     "I have been careful. You don't need to worry. She won't hurt me."
     "What makes you so sure?"
     "Because, even though she won't admit it, she loves me... and I love her."
     "Does she know of our true allegiance?"
     "No."
     "You realize you will have to make a choice in the end right? Your friends or her."
   "I know, but I'm choosing to focus on now."