This is a take on the Cornwell/Lorca knowing each other from somewhere other than the academy idea but in theory could be canon. Title taken from the song in 'Phantom of the Opera' and the Terry Pratchett novel of the same name.

Whoever had come up with this idea was a genius, Katrina decided. While the official reason for holding Starfleet's first ever Masquerade Ball was 'for the officers to socialise without the constraints of rank holding them back', what actually seemed to be happening (to Katrina's complete lack of surprise) was that people were getting laid without the constraints of rank holding them back. Everywhere she looked people were pairing off, either tucked into convenient corners of the room or even leaving it altogether, presumably to finish what they'd started without interruption. She wasn't entirely averse to the idea herself and had dressed accordingly – her black feathered mask covered enough of her face to make her unrecognisable and her backless silk dress revealed enough of the rest of her that it should be obvious she wasn't just after polite conversation. So far, however, despite the flatteringly substantial number of inquiring glances she had received, nobody had stood out as worth her time.

She collected another drink from a passing waiter and turned to scan the room again. As she did so, she caught the eye of a man on the other side of the room. He was wearing tight trousers that showed off his extremely muscular legs and a loose fitting shirt left open to expose his equally muscular chest. He had obviously been watching her and, seeing her spot him, raised his glass to her across the room. Something about the way he moved was familiar, but she couldn't quite place it. Intrigued, she raised hers in turn and he started to make his way over to her. He moved with an animal grace, not quite predatory but close enough to get her pulse racing. At length he reached her, raised his glass again and clinked it to hers.

'Good evening. Forgive me not introducing myself, but I think that would rather spoil the point, don't you?'

Oh. Oh. Now she had it.

Gabriel Lorca. A Lieutenant. Brilliant, ambitious. Young for his rank, like she was for hers. Attractive, though sometimes over-confident and prone to using his looks to his advantage too much for her taste.

Also, her second in command and her direct subordinate. A man she'd seen every day for the past three years, and would for the next two. No wonder he'd seemed familiar.

Leave now! her brain screeched at her. The point of tonight was to hook up with someone she didn't know, not someone she did. And yet, she'd be lying if she said she hadn't thought about it. She'd be surprised if there was anyone on their team who hadn't. Up until now, however, she'd never considered it as a serious possibility.

'And what point is that?' she replied, playing for time. She was almost certain he'd worked out it was her before he'd even reached her, which meant he knew what he was doing. If, on the other hand, he hadn't, would that make it better or worse?

'To leave rank at the door.' His voice was low, seductive – there was no mistaking what he was after. Anyone who knew him well, however, would be able to detect the slight note of uncertainty he was trying to cover up; he was nervous and he was trying to hide it.

And that right there was the problem. She did know him well, had spent the last three years getting to know him. As the two senior officers on their research team, a certain amount of closeness had been inevitable. He was the one she'd got drunk with when her last relationship had broken down, and she'd been there for him in turn when his father had passed away. They were friends, they were a good team and it worked. It would be madness to mess with it.

She pulled back a little and smiled at him with a hint of regret.

'I really don't think this is a good idea.' What she could see of his face beneath the mask fell. 'Why me? You could have anyone here.' He pursed his lips as if insulted.

'I don't want just anyone. I want you. And tonight, I thought there might be a chance.. never mind. Forget it.' He turned to leave, and suddenly, she knew she had to have him. She caught him by the hand and surprised, he turned back to her.

'Alright. But just tonight. After all, I have no idea who you are.' He laughed out loud at that and pulled her to him, crushing her body against his before capturing her lips in a surprisingly tender kiss. And oh, she was glad she hadn't said no to him now; his mouth was taking her apart and his strong hands were tracing the outlines of her body in a way that promised so much more than would be proper whilst surrounded by so many people. She pulled back, breathless.

'Let's get out of here,' and he hummed his agreement. Taking his hand, she started weaving her way through the crowd towards one of the smaller exits. He stayed close behind her, placing his other hand on her hip in a somewhat proprietary manner that she was surprised she liked. Once they were out of the hall, she lead the way down the corridor to a small reading room that had once been her favourite due to the fact that so few people knew about it. She sighed in relief on discovering the room was indeed empty and turned to pull him back towards her. His kisses were more heated now, his tongue slick against hers as they fought for dominance. He backed her up against a table, then lifted her swiftly onto it and stepped close between her legs. She could feel his erection pressing against her through the tight fabric of his trousers and moaned in anticipation. His kisses trailed down her jaw and neck and she tangled her fingers in his hair, hooking her legs behind his to pull him closer. Reaching the neckline of her dress, he paused for a moment and looked up her with lust-clouded eyes for permission. Katrina reached down and in one swift movement pulled the dress up over her head, leaving her in nothing but her mask, her knickers, heels and stockings.

'Oh fuck,' Gabriel groaned, taking in the sight of her. 'You are so beautiful,' he whispered, moving close again and returning his mouth to where he'd left off. His hands ran down her sides and stopped at her thighs, tracing little patterns on the inside of them that left Katrina desperate for more. His mouth had reached her nipples now and the movements he was making with his tongue were undoing her. She wriggled her hips, trying to get his hands to move where she really wanted them and he gave a low chuckle.

'Please,' she moaned breathlessly, 'I need more,' and was rewarded by one of his hands trailing lightly up her thigh to stroke her through her panties. She bucked and mewled and he chuckled again, this time in appreciation.

'So wet for me,' he murmured, and she couldn't respond. He moved back for a second but she barely had time to protest before he was back again, pushing her underwear to the side and lining himself up. 'Tell me you want this,' he whispered into her ear. 'Tell me you need this as much as I do.'

Katrina was struggling to form words. 'Please, just fuck me!' she gasped. 'I need you to fuck me.' With a groan, he pushed in and then held still for a moment. She could feel him hot and hard inside her and she wriggled desperately, needing him to move. 'Please!' she begged again and he pulled out slowly, setting the most languorous pace she'd ever been subjected to. She found herself writhing and bucking, moaning and pleading with him in the most complete lack of control she'd ever experienced. He refused to move faster, though she could feel him trembling with the effort of holding back, slowly pushing them both closer and closer to the edge. She could feel her climax building and tried to formulate words. 'I need..' she moaned raggedly, 'Oh god I need...' He didn't wait for her to finish, cutting her off by slipping a hand between their bodies and sliding a finger deliberately onto her clit. He dragged his fingers over her in time with his torturously slow thrusts, pushing her over the edge into crashing waves of sensation. She arched against him, fingers digging hard enough into his back to leave marks, her spasms of ecstasy pulling him over the edge with her. She felt him stutter, finally losing the rigid control he had maintained over himself as his orgasm hit hard. Groaning into her neck, he gave a final few thrusts as he rode it out and stilled, panting, against her. She held him as their breathing slowed, feeling the muscles under her hands relaxing as they came back to reality.

'That was fucking incredible,' she admitted, and felt him rumble with laughter underneath her. He kissed her lazily, neither of them fighting for control anymore but moving together. He handed her her dress and she pulled it back over her head, before he helped her down from the table and adjusted it minutely for her.

'Dance with me?' he asked. She chuckled.

'I don't think I've got the legs for dancing after that.'

'Don't worry, I won't let you fall. I just want to hold you.' He took her hand and led the way back to the main party. Katrina had no idea how much time had elapsed but the dancefloor had thinned out noticeably and the music had changed to something slower. Gabriel pulled her to him and she relaxed against him, his arm around her waist, her head resting on his shoulder and their fingers laced together. They swayed in time with the rhythm, losing themselves in the feel of each other. Eventually Katrina lifted her head. There were only a few people left on the dancefloor now and she didn't want to get caught in a situation she'd have to explain.

'I have to go,' she said softly, stepping back and letting her fingers slide out from between his. 'It was… nice to meet you.' The words were horrendously inadequate but she couldn't think of anything else to say without compromising either herself or him. He smiled wryly as if he understood her dilemma.

'You too.' He stepped forward and met her lips for one last kiss; goodbye this time. They lingered on each other's tongues before he bent his head to her ear. 'Thank you,' he breathed, before pulling back. They both straightened, subconsciously mirroring each other's poses and smiling when they realised. Katrina dipped her head in farewell and turned, leaving the room without looking back. She wasn't sure what she might see.

'Commander.' She turned, trying to ignore the flutters that had started in her stomach at the sound of his voice.

'Lieutenant. You are very nearly late.' He was the last to arrive for their morning briefing, an extremely unusual occurrence, and she'd been starting to worry. The rest of the team were assembled already, most with mugs of coffee and one with a prominent hickey poking out of the top of his uniform collar; all evidence of a good time the night before.

'My apologies. I picked up supplies on the way over.' Gabriel raised his hands; as well as the mandatory coffee in his left hand he also held a large bag of doughnuts in his right. She grinned at him.

'Good thinking, Lieutenant. I think we could all do with a pick-me-up this morning.' Her gaze had wandered to Ensign Roberts' neckline as she spoke and the man blushed.

'Why Commander, didn't you have a good time last night?' Katrina snapped her gaze back to Lorca but there wasn't even a twinkle in his eye. Katrina made sure her face was equally bland before replying.

'On the contrary Lieutenant, I enjoyed myself immensely. And yourself?'

'Oh, I had a very good time.' Unlike her, he allowed some innuendo to creep into his tone and there were a couple of answering snickers from the other members of the team. Gabriel had a reputation, after all, and it would have been unusual for him to attend an event like the previous evening's party without some kind of reference to his escapades afterwards. She allowed herself a wry smile and raised an eyebrow.

'I see. Well, as long as it doesn't interfere with your ability to do your job today.' His face shuttered off immediately, and she almost regretted saying it.

'No sir.'

'Good.' She turned away.

'Although,' he began tentatively, and she looked back at him, curious, 'I am thinking of recommending they make the occasion an annual tradition.' She waited a moment, appraising him.

'I agree. Let's hope it happens again next year.' He smiled and for a moment he was the man she'd seen behind the mask last night, before being replaced with Gabriel Lorca, her colleague and friend. She looked away. 'Now let's get down to business.' They took their seats, the doughnuts were shared out and the day began.