"Harry?"

He had grown used to hearing her voice in the darkness since he'd been staying with her; it was soft and uncertain, and her mere presence in the next room made the night feel much less claustrophobic and troublesome than when he was alone in his own home. His bathroom being blown to smithereens had been a blessing in disguise, really; if it wasn't for that, he wouldn't be staying in his best friend's seemingly unnecessary spare room, and wouldn't be there to talk until two am on the nights she struggled to sleep, which, to be fair, was most nights. It felt horribly domestic, but correct in ways he hadn't quite let himself think about, yet.

He opened one eye and saw Nikki's small silhouette at the door, haloed in the warmth of the hallway light.

"Yeah?"

"Are you awake?"

Harry scoffed. "You know I am, and if I had been asleep, you would've just woken me. Like usual."

"Sorry," she said, not sounding sorry at all. He watched her close the door quietly behind her and felt her feel her way along the bottom of the bed, finally settling cross-legged about halfway up. Feeling blindly, he located the bedside lamp and pulled its string; it cast a warm glow across the bedsheets, just enough to see one another without straining nor blinding their tired eyes. He sat up too, and mirrored his friend's position, so they were sat directly opposite, cross-legged and cosy.

"So?"

"So what?" Nikki laughed.

"What can I do for you?" Harry quirked an eyebrow and she giggled again.

"Maybe I just wanted to come and annoy you for the hell of it."

"You did that when you stole the insides of my burger earlier."

"I wouldn't have had to steal if you'd have ordered the right burger for me in the first place."

Mock offended, Harry slapped his hand to his chest. "You're suggesting that it's my fault that you're a deceitful little thief?"

"Absolutely."

They both chuckled again, and Harry felt his heart stutter stupidly when she finally stopped giggling and looked up at him with wide dark eyes.

"Do you really sleep, Harry?"

He considered. He slept, yes, of course he did – she did too. But did he rest? He hadn't for a long time, would stare at the ceiling or drink scotch until he passed out, usually. But since he'd been here, since he'd been away from his big empty bed and fancy kitchen equipment and blown up bathroom, since he'd been living with someone, simply... he had slept properly, had got some real rest. He had rested particularly well the night Nikki had fell asleep splayed half across his chest, and hasn't rested at all the following night when Nikki didn't mention it or even visit him for a mug of hot chocolate and before-bed hug.

"Sometimes," he said. It seemed the simplest answer.

"I sleep but I'm still tired," Nikki frowned. "It's the job."

"Nightmares?"

"Sometimes. Less now." God, that little smile. "But I just... I just keep thinking, Harry. The job makes you think too much. We find reasons for things, reasons for people dying, and we do it well, but then at night I just lay there thinking about all the things that I don't understand the reasons for, and it... it drives me mad, Harry. Do you really not feel it?"

"I feel it, but I've learned how to turn off that bit of my brain, Nikki." It wasn't a total lie. It depended on the case, the circumstance, the person...

"I don't believe you." Nikki squinted at him, and shoved his leg. "You're more of a softie than you let on."

"Hm." Harry picked absently at a thread on the bedcover; Nikki tutted and slapped his hand away with an irritated huff. "Maybe I am."

There was another silence, not uncomfortable, just quiet, gentle. Then, Harry asked, with more than a few qualms about asking, what Nikki was bothered by tonight; what unreasonable thing was echoing through her brain and causing her sleeplessness on this particular Tuesday evening. He was expecting the usual heavy night-time topics – morality, mortality, ethics – but instead, she nudged his hand with hers, so softly he wondered if he'd imagined it:

"I've been thinking about us."

Harry's brain screeched to a halt at her words. His eyes searched hers for a glint of humour, that cheekiness of hers that he had always been so amused by. She just looked back at him earnestly, bringing her hands up to fiddle with her necklace after a few moments, as though nervous. When it became apparent that Harry was not going to give any kind of verbal response – just a startled, wondering look – she continued.

"I've been thinking about us, Harry. For all of the science that's shaped my life, that shapes my beliefs and faith and opinions and self... none of it explains us."

"Us?" Harry managed to croak after a moment.

"Us," Nikki shrugged. "Nothing can explain a love like ours."

And now Harry's brain just melted. He could feel his organs flipping and flopping and that's not how anatomy works, but that's how he felt, and it felt real, and, God, Nikki...

"Now he shuts up," she laughed. "You usually have an answer for everything."

Nikki had never looked quite so painfully beautiful as she did in that moment; radiant, happy, angelic, sat there in Harry's bed in her blue silk pyjamas like that was where she belonged. Which, Harry reasoned, maybe she did.

Harry did the only thing he could think to do; he leaned in and kissed her. And Nikki kissed him back, with a new confidence he hadn't recognised in her when they'd kissed before, that one, tipsy, spontaneous time in the pub in the early days of their friendship. Her fingers threaded through his hair, pulling him close, kissing him harder, gasping into his mouth in an obscenely sexy way.

That seemed like answer enough, for now; Harry figured that any other questions that kept Nikki awake to the early hours could be tackled together, from here on out.