Author's Notes:

I am a big believer in appropriate warnings, so let me be very clear. The vast majority of this fic is adult content. It is an incestuous pairing, with consensual underage sex (17). It is 100% self-indulgent and goes 0-100 pretty much immediately. Please be aware of what you are getting into- my aim is not to surprise anyone with something unexpected that will make them uncomfortable. Only proceed if this is your jam.

Jacob's mobile buzzed on his bedside table. He bounced it in hands for a few moments before he picked up, staring at Evie's name on the caller ID.

"'Lo?"

"Jacob, hi, Father's forgotten about me again. Can you come pick me up?"

Ugh. "Can't you just take a bus?"

"Yes, but it would take too long. I want to shower before ballet. Please?"

He bit back a sigh. This was a bad idea. "Fine. Give me fifteen."

Jacob went to the bog-standard comprehensive around the corner, but that hadn't been good enough for Evie and her ambition. No, she had to take the exams and end up at one of the posh grammar schools- which, of course, was all the bloody way across town.

The air was brisk as he rode over, tucked into his jacket and helmet. It was fairly typical these days for Father to forget to be somewhere. He was still hidden in his office at the university and reeling from Mother up and disappearing; to be honest, they all were.

When he pulled up, she was standing out by the curb and waiting. He felt his mouth go a little dry as he took in the blazer and skirt, the pert ponytail. Down, boy.

He motioned her over and she climbed onto the back, tucking herself flush against him and wrapping her arms around his stomach. Even through the jacket, he felt like he was burning where they were pressed together; when he glanced down, he got an eyeful of thigh where her skirt had ridden up and immediately had to snap his eyes forward. If they didn't get moving quickly, passersby were about to get an eyeful of the tent in his pants.

This had been such a bad idea.

She shot him a thumbs up and he kicked the engine into a roar, navigating back out onto the streets.

Evie felt like she was going to combust by the time they reached the house.

Between her face against Jacob's back, feeling the muscles shift every time he moved his arm, the smell of him- leather, something vaguely earthy, and sandalwood- and the vibrations of the motorcycle seat itself, she was terrified that she was going to leave some dampness behind when she stood.

He parked in front of the house and they walked silently through the small garden. She stood on the stoop and waited as he dug around for the key, doing her best not to squirm. All she had to do was get inside and upstairs to her room- then she could rub one out and desperately pretend the whole time that she wasn't thinking about her brother.

He found the keys and promptly dropped them, cursing as they bounced towards to her feet.

She leaned down. "Here, I got it—"

Bent over, she looked up and found herself face to face with an eyeful of what was obviously an incredible erection straining in the fabric of his pants.

There was the world's most awkward silence.

"Uh," he said, "oh my God, uh—"

She straightened but barely heard him. Dear God, it was big. Was that average? It couldn't be.

He snatched the key and immediately fumbled with the door, throwing it open and charging through to the kitchen. She took her shoes off slowly, head spinning. Did that actually just happen? Was it- was it for her?

Creeping through to the kitchen, she leaned in and found Jacob at the table with his head in his hands. She took a few steps towards him. "Jacob…"

"I'm so sorry," he mumbled. "Fucking embarrassing, Jesus Christ."

"Is it… Was that- why…"

"Well, you know, I'm a young bloke still." He shot her a forced grin. "Plus I really love that bike, so."

She felt like her face was bright red. Her heart was going a million miles an hour and she opened her mouth but couldn't feel an answer coming.

Any second now, she was sure, his face was going to turn to horror as he recognized the emotion she was experiencing. Instead, his grin trailed off as they stared at each other, his hand curling into a tight fist on the table.

"Was it…" She licked her lips and tried again, barely believing that she was saying the words as they drifted into the world. "Was it for me?"

He made a choked noise. "What- I- no, of course not—"

But he was lying, she knew a lie from him at twenty paces in the dark. "It was for me."

"Uh," he managed, as she put her fingers to his cheek. His throat was working rapidly as he swallowed, and she was suddenly seized by the urge to lean down and run her tongue along the skin there, beginning to grow a maddeningly handsome sort of scruff.

Instead, she just stood and watched as one of his hands lifted very, very slowly, almost as if waiting for her to bolt. It got close to her knee and then drifted higher, fingers skimming as he worked up the inside of her thigh, never looking away from her eyes. A light sort of panting filled the room and with a jolt a horror she realized it was her; she stood stock still as his hand travelled higher still, up and up past the hem of her skirts before she felt a touch, ghost light, along the bottom of her panties where she was now desperately, horribly wet—

The front door thunked open. Their Father's voice called from the entrance as he obviously spotted her shoes by the door – "oh God, Evie, I just realized I didn't pick you up, I'm so sorry. Darling, are you here?"

Jacob's hand snatched back like he was burned and she staggered away from him, frantically finding her voice. "Here," she called back, "in the kitchen."

Father was in the room moments later. "I really am so sorry, Evie."

"It's fine," she choked out, unable to look either of them in the eye. "I'll be up in my room; I've got assignments to finish."

He and Father sat in an awkward silence for a few minutes before Jacob stuffed his hands in his pockets, abandoning the kitchen to go upstairs. Once alone, maybe he could try and understand what the hell had just happened.

It was like a fever dream, fantastic and unreal. She had been so damp that he could easily feel it through the fabric, her pupils blown as she stared at him with slightly opened lips.

He ought to just be relieved that she didn't punch him right in the face, but instead he found himself wondering if- did that mean—

Fuck, this was bad.

Rubbing his face with a groan, he had made it most of the way to his room when he could've sworn that he heard someone say his name.

Backtracking a bit, he shuffled until he stopped at Evie's door. And there it was again, faint but definite, a breathy whisper.

His hands were shaking now- this was surely a residual bit of leftover madness from what had just happened downstairs? But then- what if it wasn't madness, and what he thought was happening was actually happening behind that door—

He had to know.

The door was cracked open, he realized now, the slightest bit of light coming through. Clearly it had crept ajar without her realizing. Pressing his fingers to the wood, he pushed it further just another fraction of an inch, enough to be able to see Evie lying on her bed, back arching as she moved, her hand between her oh holy shit.

The strangled noise was out of him before he could help it. She froze and snapped up, hands immediately flying to her sides, her eyes open wide. Her face was bright red and he could see now that some strands of her hair had pulled loose from her tight ponytail. "Did you- did you hear- this is not what you think—"

Quickly stepping in against his better judgement, he closed the door, heart in his throat. "It isn't? Because I know what it looked like."

Her mouth was open as she stared, her breath coming out in little gasps. God, she looked so fucking hot, it wasn't right or fair and it was a cruel cosmic joke that they were related. So much daily energy had to go into ignoring her lithe form in tiny sleep shorts or that infuriating little uniform.

It was bad enough that he'd just stuck his hand up her skirt. It was really bad that he desperately wanted to do it again.

When he reached the bed, he sat down next to her legs. In the same movement as before, he gently placed his fingertips at her knees and worked upwards, carefully watching her face. Her gaze, for its part, was glued to his hand. She didn't stop him; if anything, she parted her legs wider, making it easier for him to move upwards.

When he reached the seam of her knickers, she clamped her eyes shut and curled her fingers in the sheets, letting out a little gasp.

Slowly, slowly, ever so slowly so she had time to stop him if she wanted, he slid his fingers up until she suddenly shuddered under his touch.

"Show me," he breathed. For a second he was sure that speaking out loud had ruined the moment, that she would now shove him away and scream at him for being a pervert. Instead, she kept her eyes closed and moved her hand to cover his, lightly pressing down on a small space near the apex of her thighs and motioning for him to make small circles.

This wasn't happening. This couldn't be happening. He obeyed the movement and she started to shudder, quivering under his touch.

Jacob shook his head like his ears were waterlogged. This wasn't- he wasn't touching his sister's knickers. They hadn't skipped kissing and cuddling and gone straight to him getting her off. He was not so hard that it nearly hurt.

Her head was tossing from side to side now, her body desperate to move and to stay completely still at the same time. Had she ever done this with someone else before? The image drove an irrational stab of jealousy through him, the thought abhorrent.

The pants in the room were becoming faster and more high pitched, he realized, her neck arching backwards so her tits pushed towards him invitingly. She was desperately trying to be silent, clamping down on her lips, but little whimpers kept sneaking out past her gritted teeth.

He should slow down, backtrack, strip her down and kiss every solid inch of her-

With a tinny noise, her phone began to sing, some classical piece that trilled through the air. She froze and let out a little groan. "I have to get ready for ballet."

Skip it, he wanted to say. Don't go. Instead, he tried to keep his voice neutral and normal, withdrawing his hand. "Right. I'll leave you be, then."

He left the room in a hurry. He was terrified that if he didn't speed away, he would end up pinning her to the bed and devouring her until she couldn't even remember how to do a plié.

Ballet was torturous. As if she could focus on anything after what had happened.

She tried. But she kept closing her eyes and seeing Jacob's steady and lidded gaze, the burning focus of it sparking on her skin.

By the time she returned home, Father and Jacob had clearly already eaten. The light was on in Father's study; in all likelihood, he would fall asleep there, and she would find him slumped over his notes in the morning.

Jacob could be anywhere. He was rarely home.

But when she padded up the stairs, she saw that the light was also on in his room, the soft thump of music carrying through the door.

She showered. She put on her sleep things. She brushed her teeth. She tried to think of anything else, of anyone else. Even so, she ended up standing outside of his door, hand hovering over the handle.

Right at the moment that she decided to leave and end this madness, the door swung open from the inside. "I can see your shadow," Jacob said irritably. "Either come in or go away."

So she went in, awkwardly hovering in the doorway as he stalked back to his bed, pulling his laptop back onto his lap.

He kept his eyes on the screen as she fidgeted. "Uh…" she started, "I mean, that is…"

It was too frightening.

She shook her head. "Never mind, it's nothing."

The threshold was within reach when Jacob crossed the room behind her in three steps, reaching over her shoulder and holding the door shut. They froze like that for a moment, her facing the door, his presence looming behind her. Slowly, she turned to face him, and his eyes had taken on the same dark quality from before that made her heart race.

In a flash, he braced her against the door and pushed his hand down the front of her shorts, directly in contact with her skin. She snapped her hands to his shoulders and held on tightly as he found her clit, starting on the little motions she'd showed him earlier.

She'd showed him- oh God, that really happened, this was really happening-

"Is this what you wanted? Why you came here?" His voice was husky and his breath hot on her shoulder as he worked, her toes twisting against the floor.

When she didn't answer, he grabbed her ass with his other hand and tucked her closer, pressing his hard-on to her thigh as he sped up his movements. "I said- is this what you wanted?"

The orgasm was shattering and quick when it suddenly ripped through her, bursting like a firework as she let out a shuddered "yes," a scream but for the lack of air behind the sound.

He withdrew when she slumped against him on shaking knees. As she watched, he lifted his slick fingers to his lips and sucked.

Heart in her throat, she whirled and fled, shaking from head to toe.