Rabastan was curled in an armchair in the library the next day when Bellatrix marched up to him. She stood in front of him with her hands planted on her hips and said, in the most matter-of-fact tone that Rabastan had ever heard her use, "Your brother says you want to know how to please my sister."

He blinked up at her, completely thrown by her tone. "What?"

"Your brother says that you can't please my sister and you want to know how. Isn't that right?"

Rabastan flushed. "He told you –"

"Your brother tells me everything," Bellatrix said smugly. Like Hell he does, Rabastan thought, but he said nothing.

"And even if your brother hadn't told me," she continued, "Andromeda did. She said that you were absolutely wretched, the worst she'd ever had." She broke off, clearly watching Rabastan for his reaction. He swallowed, not wanting to give her the satisfaction of showing that that hurt.

"So, I thought I'd do a good thing and teach you to do better," she continued, hands moving to her blouse, and Rabastan's eyes widened.

"What? No!" He scrambled back from her, causing the legs of the chair to scratch along the ground. "What are you doing?"

She dropped her blouse to the ground and rested one hand on her hip, arching her back a little. Rabastan's stomach churned.

"You want to know how to please my sister, don't you?" she asked. "You don't want to marry her without knowing the sort of thing that she likes?" She moved forward, climbing onto the chair, practically sitting in Rabastan's lap, though she was much larger than him. She took his hand and laid it on her breast. "There, now–"

"No!" Rabastan cried, jerking his hand back. "You- you and my brother are- and I don't want you anyhow!"

"Don't be stupid, Rab," she purred, grasping him by his hair and leaning forward to kiss him. "Everyone wants me."

"I don't!" His voice choked with tears. "I don't want you! Please- get off…"

"No. I'm going to teach you what to do to my sister – it's for your own good, Rab." She grasped his hand and put it on her breast again. "Squeeze."

Rabastan's throat tightened. He was sure that he should have been having some sort of physical reaction from this, but all that he felt was a vague sense of nausea. He tightened his fingers a little around Bellatrix's breast and she exhaled softly.

"That's it." She reached behind herself to unhook her bra and her breasts spilled out, full and firm and pale. "Again. And not too hard – I like it rough, but Andromeda doesn't."

"I… Bellatrix, I–"

"Shut your mouth, you whiny little sod," Bellatrix hissed and he winced at the slur. "Touch me." She waited until he had put his hand on her breast again and then kissed him deeply, her tongue prodding into his mouth. He almost gagged.

"Don't act like you don't like it," she murmured, pulling back for a second. "You do. Everyone does."

"I don't want you!"

"Didn't I tell you to shut your mouth?" She took his hand and slid it up along her thigh, beneath her skirt. His fingernails caught on her stockings and they must have scratched her, but she didn't seem the slightest bit fazed by it.

"Here…" she murmured, pressing his palm between her legs and rolling her hips slowly against his hand. "Touch me here. That's what you do… if you ever want to please a girl, you've got to know how to touch her here…"

Rabastan couldn't speak. His voice was being constricted with tears. He bowed his head and bit his tongue. He rubbed his hand against her knickers, praying for it to be over quickly.

"Not so hard, you fucking- ouch!" Bellatrix grabbed his wrist. "Gently! You'll make Andromeda cry if you touch her like that. Oh, that's right – you did make her cry," she added with a sneer. "And here I thought she was exaggerating when she said how useless you are…"

"If you think I'm useless, then why–"

"I'm doing you a favour," she reminded him. "Now…" She lifted her hips and shimmied out of her knickers, kicking them aside, then hitched up her skirt. "Here," she breathed, taking Rabastan's fingers and pressing them against her. "Rub me just here…"

Rabastan moved his fingers against her and Bellatrix moaned quietly. "Yes, like that… see… to please my sister… all you'll have to do is keep touching her like this until she finishes…"

He didn't say anything. He moved his fingers automatically, mechanically, preferring that over trying to argue. Bellatrix's face was flushed, and she took his free hand and laid it on her breast, guiding his fingers to her nipple. "Oh… yes, that's right. Keep doing this and you might almost be able to satisfy her…" she murmured, and she sounded to Rabastan more like she was talking to herself than to him. "Never really be able to please her, of course," she continued, "but almost… oh, Andromeda…" Her voice trailed off into an inarticulate moan, but it seemed painfully obvious to Rabastan that she was doing everything in her power not to think about him.

Which was just as well.

Her body shuddered and then she pushed his hands away, slumping down half on top of him. Rabastan stayed stiff and still, unsure what to do.

"That wasn't bad, Rabastan," she whispered breathlessly, and then her hand trailed down his chest. "Right… here, it's your turn…" Her fingers brushed his crotch and then went still and she looked up at him. "What, you're not even hard for me?"

"Please get off me, Bellatrix," he whispered, voice cracking. "I… I don't want…"

"Most boys would be bursting out of their trousers right now," she said, with a bit of a sneer. "What's wrong with you?"

"I'm not like most boys!" he told her sharply.

"What's that- oh…" A sneer curled on her mouth and her eyes gleamed. "Oh, I see what the problem is here, I see…" She tipped her head back and laughed. "I suppose that I shouldn't be surprised…"

"What's that supposed to mean?" he demanded, panic rising in his chest. His vision was going spotty and he jumped up, backing away from her. Bellatrix ran a hand through her hair, then stretched out her arms and legs, reclining in the chair.

"Well, why didn't you just say that you don't like girls?" she asked, voice all sugar. "You could have saved me and Andromeda both so much frustration… well, that makes everything so much easier–"

Rabastan felt sick for a moment, but that was almost instantly eclipsed by fury. He lurched forward and grabbed her by her arm, digging his ragged nails into her skin.

"I'm not like that," he hissed, more automatically than anything else. "And even if I did," he added, "it's none of your business who I fancy and who I don't. I'm going to be marrying your sister no matter what, and you should just keep your nose out of it!" He shook her – barely managing to move her, but that wasn't the point. She looked absolutely shocked at him. "You just stay with my brother and don't presume that you understand anything about me!"

Bellatrix didn't say anything. She stared at Rabastan, dumbstruck.

"Don't tell anyone," he told her, voice shaking. "Don't tell anyone about what you just did to me, and don't you dare tell anyone that I fancy men. Because I don't!"

Bellatrix nodded, still speechless, and Rabastan whirled around, half storming and half running out of the library.

He was almost at the door when he heard her call after him, snorting.

"Like Hell you don't."

He didn't turn back.