Author's note: because I couldn't get that image of Jack out of my head :)

Enjoy!

They were sitting together at breakfast one day when Phryne looked at him from the corner of her eye and mentioned casually, 'You know, it's my birthday soon.'
He sighed. 'Don't remind me.'
'What? You don't like birthdays?'
'I have no idea what I should get you for a present. You have everything.'
'You don't have to get me anything.'
'That doesn't sound right.'
'Really,' she said innocently, 'I want nothing at all.'
He noticed the tone. 'Except…?'
'Except nothing!'
He raised an eyebrow.
'Well… maybe there's one little thing…'
'Here we go.'
'I just want you to do something for me. It's not at all difficult.'
'What is it?'
She looked at him playfully. 'Promise you'll do it?'
'Before I've heard what it is? Not in a million years. Who knows what you'll make me do.'
'Jack! Don't you trust me?'
He smiled at her amiably. 'Not even a little bit.'
She seemed rather pleased. 'Hmm. Very wise, I'm sure.'
'So?'
'Well, I would like to do something fun for my birthday…'
'Why do I have a bad feeling about this?'
'… and I had the most marvelous idea!'
He braced himself. 'Let's hear it.'
'I want a fancy dress party,' she said, eyes sparkling.
'Oh God,' he sighed, rubbing a hand over his eyes with a pained expression.
'We'll all dress up – it will be a fabulous.'
'Look, Phryne, I don't look good in costume.'
She looked at him appreciatively. 'I'm sure you'd look good in anything, Inspector.'
'You'd think that, but no.'
'Please, Jack?' she wheedled, looking up at him with big eyes. 'It's the only thing I want for my birthday.'
'Oh, that's not fair.'
'You know…' She was leaning close now, her head tilted in that way she had. 'You owe me a Roman soldier.'
'What do you mean?'
'Don't you remember? At cousin Guy's wedding. I almost had you dressed as Mark Anthony.'
'Oh. Right. That was close.'
'So you owe me a Mark Anthony, Inspector.'
'You know, I'm not sure that big feathered helmets are really my style.'
'I think you would look very dashing.'
'Forget it, Miss Fisher.'
'Don't be such a spoilsport, Jack! I'm having the party, whether you like it or not.'
'And I'll be there. Properly dressed in a suit, whether you like it or not.'
'Fine,' she said huffily. 'If you insist on being boring, there's simply no arguing with you.'
And she walked away, not noticing that the corners of his mouth were pulling down ever so slightly.

Two weeks passed until Phryne's birthday, weeks in which she was busy planning the party and in which not a day went by without her trying to convince Jack to wear a costume. She sprung it on him over breakfast, during investigations, when they were in bed together. He finally put his foot down when she started asking Collins which costume he thought would suit Jack best: a gladiator or Hercules.
He firmly steered her away from his flustered constable, into his office. He shut the door behind them.
'Will you stop badgering me about this damned costume? And leave Collins out of this.'
'Come on, Jack, I must be able to entice you with something.'
'Don't count on it. I simply don't like costumes. They make me feel ridiculous. Can't you just accept that?'
She chose to ignore him. 'How about a pirate?'
He snorted. 'I'm not sure I have the necessary swagger.'
'A Roman senator, then? Quite dignified, I'd think.'
'I'm not walking around in a sheet.'
'It's a toga, Jack!'
'Still no.'
She suddenly looked up at him as if a great idea had occurred to her. 'I know! Count Dracula. Very fancy. You'd just need a cape.'
He did not even deign to respond this time, merely crossed his arms and looked at her impassively. She gave him a disgruntled look. 'Just when I thought you'd loosened up a bit in the last few months.'
'A man can't abandon all of his principles, Miss Fisher. This is where I draw the line.'
'At costumes?'
'I don't like dressing up. But feel free to dress up yourself. I'm sure whatever outfit you choose will look great on you.'
'Jack…'
But he ushered her out of the door before she could say anything else, and she left feeling a little confused. She wasn't sure why her powers of persuasion had suddenly failed her, and she was a little disappointed that he wouldn't be dressed up for her party, but she had to admit to herself that she liked him all determined. She sighed. If only he could have been all determined in a gladiator outfit. That would have been perfection.

The day of the party arrived. Most of the furniture had been cleared away to make room for the guests, copious amounts of champagne had been delivered, and at least half of Melbourne's fashionable society were rumored to make an appearance. Speculation ran high as to how various people would be dressed, and many an uninvited lady sat at home sulking because they would be denied the pleasure of seeing Mr. Soandso in a dashing costume, and the equally great pleasure of gossiping about Miss X's much too revealing outfit.
Phryne looked forward to her party. She had had a beautiful little black dress made so she could dress up as a chorus girl. It was a loose-fitting, sparkly thing with a plunging neckline and showing rather a lot of leg, and she usually had too much class to wear such things. That was why, she reflected with a satisfied smile, parties like these were the perfect opportunity to wear something out of the ordinary. She couldn't wait to show it off. The only thing that marred her anticipatory excitement was her slight worry that Jack would not have a good time. But whenever that thought occurred to her, she shrugged it off: after all, it was not her responsibility to make sure that he enjoyed himself.

At eight o'clock, the first guests started to arrive, in elaborate costumes and a generally elated mood. It was clear that everyone had been determined to impress, and the house was soon filled with feathers, sparkling jewelry, and a heavy cloud of perfume. Refreshments were served in the dining room, while the floor had been cleared in the parlor. The music was excellent and the champagne even better, so it wasn't long before the dancing started, and Phryne enjoyed herself tremendously, getting asked to dance by a succession of handsome knights, dashing outlaws and even the occasional pirate. It wasn't until the last guests had arrived that she realized that Jack was not in the crowd. She excused herself to the toreador she was dancing with, and moved to the edge of the room, frowning slightly. She knew Jack disliked crowds and rowdy parties, but he wouldn't really consider not showing up on her birthday, would he? Then she suddenly heard a soft knock on the door, and went to open it, smiling. Of course he would be there, 'perfectly disguised as a police inspector' as he had said once before. She opened the door, and her mouth fell open.
Leaning against the door jamb with a slight smile was Jack, dressed immaculately in a white captain's uniform that made him look even more handsome than usual. Phryne could only stare at him, until he straightened and tipped his cap to her with a faintly amused look in his eyes.
'Happy birthday, Miss Fisher.'
'It certainly is now,' she exclaimed in astonished delight. 'Where did you get that uniform?'
'I borrowed it from a friend who captains a merchant ship. I had a feeling you might like it.'
She bit her lip. 'God, yes. Why haven't I seen this before?'
He seemed a little confused. 'I haven't had any occasion to borrow it before.'
She flashed him a saucy smile. 'Oh, I could have thought of ample occasion…'
He cleared his throat and stepped over the threshold, looking her over from head to toe. An amused smile appeared on his face.
'So, what's your excuse for wearing this indecently short dress?'
She twirled for him, sequins flashing, beads clicking softly.
'Do you like it?'
'Mmm,' he murmured noncommittally, but the truth was that he actually liked the dress very much. It was revealing enough to be a little risqué, but not so revealing as to cross the line to vulgar.
'I'm a chorus girl,' she explained.
'In that case, I suppose I should be grateful it's nothing worse.' He reflected silently on the costumes chorus girls wore nowadays, hardly more than bathing suits, really, and he was devoutly thankful that she had not taken this opportunity to thoroughly scandalize him once and for all.
Meanwhile, she was quite distracted by his uniform, running a hand over his white sleeve, her lips slightly parted as she looked him over.
'You look very handsome, you know,' she purred.
He knew that look. He knew that tone. 'Guests,' he warned her, but she didn't care. A moment later, her arms were around his neck and she kissed him full on the mouth. Immediately, a number of wolf whistles sounded from the parlor and the dining room, and Jack disengaged himself, feeling a little hot around the collar. Phryne merely smiled unconcernedly, and soon everyone had turned back to their dance partners, their glasses of champagne, leaving the two of them the relative privacy of the hallway. Standing on tiptoe and leaning in against him, Phryne brought her mouth close to his ear.
'Let's go upstairs,' she murmured in her most seductive voice.
He raised an eyebrow. 'Not to burst your bubble, but you have a house full of people.'
'They won't notice if we're gone for a moment.'
'It's your party!'
'Exactly. It's my birthday, so I can do what I like.'
He looked at her, amused. 'Yes, but I'm quite sure you need my cooperation for this.'
'Hmm, good point. But what did you expect if you turned up like this? A girl can only stand so much, you know,' she said reprovingly.
He smiled. 'Well, why don't we make a deal? You take care to behave tonight, and I'll make it up to you.'
She was interested. 'How, exactly?'
He drew her closer and whispered something in her ear. When he stepped back, her eyes were sparkling.
'Promise?' she asked teasingly.
He raised an eyebrow at her, and answered, 'Twice.'
She bit her lip, smiling, as she put a hand on his chest, her fingers playing with the gleaming buttons of his coat. 'Well… that's an offer I can't refuse.'
'So do we have a deal?'
She looked up at him from underneath her eyelashes. 'Aye, aye, Captain.'
He suppressed a smile. 'Good. Now let's go. People are starting to stare.'
She seemed to become aware of her surroundings again, and immediately returned to her usual light manner. 'Yes, let's go. I want to show you off.'

She put her arm through his and led him into the parlor. He looked down at her as she was walking by his side, and liked the contrast between her black dress and his white uniform. They looked good together, he realized, their costumes matching nicely. The room was full of people in various states of intoxication, and Phryne took him from one smiling face to the next, introducing him to some of the most fashionable people in town, all of whose names he promptly forgot. Luckily, there were also some familiar faces, like Dr. Macmillan (who had point-blank refused to dress up), and other friends of Phryne's that he had met during their months together. He was greeted warmly by the two couples they had once spent an evening in a jazz club with, and was thinking of staying with them to talk for a while, when he saw that their other friend, a pretty young woman named Kate, had come with them. He excused himself and made straight for the champagne, giving Kate a wide berth and dragging Phryne with him. She smiled at him knowingly: Kate had shown rather a lot of interest in Jack that night at the jazz club, and Phryne knew very well that her attentions had made him feel uncomfortable. Once Jack had a glass of champagne in his hand, he maneuvered to the side of the room and seemed happy to stay there for a while.
'You should go dance,' he urged Phryne. 'I don't mind.'
She considered for a moment if she would ask him to accompany her, but she knew he didn't like to dance, especially with so many people watching, so she kissed him and disappeared into the throng. He watched her go, a crooked smile on his face as he leant against the wall and relaxed. He knew he'd have her all to himself later that night, and was glad she was enjoying herself in the meantime. For several long moments, he watched her laugh and dance, unable to take his eyes off her. Then he suddenly became aware of the fact that he was surrounded by young women in various alluring costumes, all looking up at him admiringly. He blinked. What was happening? It soon became clear that they were very keen on learning more about this handsome, unknown man who had suddenly appeared and was all the more interesting and mysterious for his aloofness. They proved very difficult to shake, and Jack was a little shocked at how brazen they were in showing their interest in him. Luckily his two-year professional partnership with Miss Fisher had made him something of an expert in parrying flirtatious remarks and ignoring even the most obvious innuendos without batting an eye. So he was pleasant and polite, but after a while it became clear that he was impervious to their charms, and the girls left him, one by one, to look for easier prey. When he was alone again, Phryne suddenly appeared at his side, smiling.
'Looks like you had quite the crowd of admirers, Captain,' she teased him.
He ignored her. 'Having a good time?'
'Marvelous,' she beamed. She kissed him lightly on the cheek, took a sip of his champagne, then was whisked away by yet another dance partner. Jack snorted, thinking that she was one to talk about a crowd of admirers, but secretly he was quite proud. She was easily the most attractive woman in the room, he thought, not just beautiful, but sparkling, sensual, drawing all eyes to her as she moved fluently to the music. For about the millionth time in the last couple of months, the thought crossed his mind that he couldn't believe his luck.

Phryne was dancing, transitioning effortlessly from one melody to the next, from one dance partner to another. She was having a great time, drinking rather a lot of champagne, and after a while, everything began to blur together slightly in a whirl of movement and color. But every so often, her eyes were drawn to a certain corner of the room, and she would invariably meet Jack's gaze, smoldering softly from underneath the brim of his cap. He was the only still point in this swirling sea of people, a fixed figure in the chaos, a little rigid maybe, a little unyielding, but strong, dependable, and there. She liked that about him. As the evening progressed, she found herself looking his way increasingly often, each time struck by how handsome he looked in his white uniform as he casually leaned against the wall, observing the proceedings with a look of detached amusement, or talking to this or that acquaintance. Finally she found herself wishing that the last of the guests would leave so she could be alone with him. She had behaved splendidly, she felt, not doing anything inappropriate to him all evening, despite the very great temptation the uniform posed, and she was increasingly eager to remove temptation by getting that uniform off as soon as possible.
Finally, in the early hours of the morning, Cec and Bert took home the last of the guests who were too drunk to stand, and Phryne closed the door behind them with a smile, feeling a slight hum of anticipation in her stomach. She turned, and found him in the doorway to the parlor, looking pleased that they were alone. He sauntered over to her, hands in his pockets.
'Looks like you had a good time. Do you want to go to bed? Are you tired?'
'Yes, yes and no,' she smiled, and when he encircled her in his arms, she leaned against him and kissed him. She noticed how starkly her black dress contrasted with the whiteness of his outfit, and pointed it out to him. 'Black and white, how appropriate. I suppose the colors suit us, don't you think? Black for the wicked, white for the good and honorable.' She was teasing him, but he responded by leaning closer to her, his voice a low murmur in her ear.
'If you knew what I was thinking right now, you wouldn't say that.'
She looked up at him, eyes sparkling. 'Do tell me!'
'I have a better idea. Why don't I show you?'
'Yes, please,' she whispered, a little breathless, as he leaned in, his mouth only inches from hers. Instead of kissing her, though, he muttered just one word: 'Bedroom.'

The bedroom door closed behind them, and immediately she leaned back against the wall and pulled him against her so she could kiss him. She lifted one leg to hook around his waist, and the hem of her dress crept upwards to reveal a perfectly indecent amount of leg, and a lacy black garter. He couldn't resist running his hand over her thigh, from her knee to her garter, sliding over the black silk stockings as he kissed her neck. She took off his captain's cap and carelessly threw it to the floor so she could run her hands through his hair – she loved him all tousled. She slightly tugged at the hair at the nape of his neck, and suddenly his mouth was on hers again, hot and greedy, and he lifted her in his enthusiasm, supporting her with both arms so she could wrap her legs around him. He pressed her harder against the wall, and she gasped slightly as she felt him, hard, between her thighs. She wanted him badly, and he seemed to notice, because he started carrying her to the bed, her legs still around his waist, their lips locked together.
He put her down on the silk sheets, not in the middle, but at the back of the bed, so she was right at the edge of the mattress. Kneeling down on the floor between her legs, still in his white uniform, he smiled at her promisingly as he slowly reached a hand under her dress. He did not undress her, did not even take off her stockings, but simply removed her panties and disappeared underneath her skirt. A moment later, she threw back her head with a sharp intake of breath, and reached up to tangle her fingers in the sheets. Very soon, he had her moaning softly as his tongue found the right spot, and he quickly realized that it wouldn't take much tonight. When he struck a rhythm, she arched her back, her breathing fast and uneven, and the moment he increased pressure, she began to tremble. He loved this moment, when her body tensed in anticipation, and he took care to keep up exactly what he was doing until she suddenly cried out, every muscle taut, then shuddered, and he gradually slowed down and stopped as she relaxed.
He emerged from underneath the dress, and reflected that he loved the way she always looked right after, flushed, breathless and happily dazed. For several long moments he just looked at her, waiting for her to recover. When she gave him a slow, lazy smile, he smiled back.
'Ready?' he asked, his voice husky with his own contained longing. 'I always keep my promises, you know.'
And he disappeared back under her skirt. She gasped delightedly, but felt obliged to say, 'Jack, you don't have to. Please don't feel obligated to… oh!' She fell back, helpless, and at that moment he surfaced again, looking at her with a grin.
'I'm sorry, what were you saying?'
'Nothing,' she whispered, her eyes large and dark. 'Oh, please don't stop now…'
And he soon had her gasping on the bed again, skillfully manipulating her with his hands and tongue until she quivered at his touch. He took his time now, knowing that she was more sensitive, carefully building tension, teasing and stroking and touching, encouraged by her moans. Finally she tensed again, and he could feel her body shake as she cried out sharply.

It took her a while to recover this time, and he waited patiently, throwing himself on the bed next to her. When she finally opened her eyes to look at him, she immediately recognized his expression and, without a word, started to take off her dress. He stopped her hand.
'Don't,' he said, a little hoarsely. 'Keep it on.'
She looked at him mischievously. 'So you do like the dress.'
'I never said I didn't.'
'True.' She moved closer to him, playing again with the buttons on his uniform. 'But if I can't take off my dress, you can't take of your uniform.'
'That's a deal,' he rumbled, then impatiently moved to kiss her. She pressed herself against him and he groaned, his hands moving to ruck up her dress, and the sight of her black silk stockings, contrasting sharply against the white skin of her thighs, made him clench his jaw as he tried to maintain control over himself. But she was already unbuttoning his trousers, eagerly, her lips slightly parted, and when she drew him out he couldn't stand it anymore. He pulled her close, then rolled over so she was lying on top of him. She sat up, and he loved the sight of her in the dress as she smoothly moved her hips in a way that was sure to drive him mad. She kept one hand on his chest for support as she sank down low onto him, and he bucked his hips to take her deeper, making her gasp, her lips parted, her fingers gripping his coat convulsively. When she moved up the hem of her dress to slide a hand underneath, he watched, fascinated, and felt his excitement rise immediately to a point that was nearly unbearable. He gripped her hips tightly to control her movements, slowing her down just a little, but the sight of her fingers moving nimbly, only just visible underneath the fabric of her dress, drove him to distraction and he knew it was no use. He pulled her down deep and let go with a low moan. An instant later, he felt her clench around him, and when she collapsed on top of him, quivering, he tangled his fingers into her hair and closed his eyes as the wave of pleasure washed over him.

Half an hour later, they had both undressed, and were lying beneath the sheets, both utterly content. She rested her head on his chest, his arms around her. Jack was just starting to fall asleep, when the sound of her voice made him open his eyes again.
'Jack?'
'Mmm?' He noticed that she was looking at his costume, lying neatly folded over a chair.
'How long can you keep that uniform?'
'I told my friend that I would bring it back tomorrow.'
'Do you think you could maybe… keep it a little longer?'
He smiled. 'I can check.'
She sighed happily and nestled a little closer. 'Perfect.'
They were quiet for a while, and as he was dozing off, he heard her mutter sleepily, 'Yes, definitely one of my better birthdays.'