A/N: This isn't a Ness fic (apologies to any roomfriends) but latest episodes of SHIELD have sucked me into a wonderful new ship (they so adorable, how could you not ship it?). Written and edited very quickly today so please pretend you didn't see any errors.

Inside The Bus, their bickering filled the hallway on Level 3.

"Argh, Fitz, I've told you. It's Science. I have to dissect things."

"No. You told me that this one would be dealt with at HQ. So why did I walk in to find it on my pristine work surface?" he snapped.

"It takes hours to fly to HQ. I had to put it somewhere!"

"Well, now you can move it," he ordered.

"Pardon?" she said and stopped walking so he did too. "I said, move it," he repeated then muttered, "And don't lie to me again, Jemma."

She threw up her hands. "Lie to you? Fitz, don't you think you're overreacting a little?"

"Overreacting? I'm overreacting? Ha. That's rich, coming from you."

"What does that mean?"

"It means I'm not the one who nearly killed herself recently."

"Fitz..." she began.

"No, I told you we wouldn't talk about it again, but in all the years we've been together and I never once believed you would -" he faltered, "- you would do that." he finished lamely.

"How can I say sorry more times than I already have? I've said it with all the words I know and I've tried to show you too - I made you that sandwich, didn't I? But here; I am sorry, Fitz. Truly, truly sorry that I scared you like that but you have to forgive me."

His eyes narrowed. "Forgive you?"

"Yes."

They stood there in an angry tableau, glaring at each other but then Simmons huffed and turned away. But before she took even one step his mouth was on hers, kissing and kissing her like a starving man. Jemma froze but sub-seconds later she was kissing him back.

Fitz made a small sound in his throat and pulled her in, his hands running up and down her back and into her hair. Jemma was on fire. She'd never thought this day would come but now that it was here she could hardly believe it. Fitz was kissing her. And he was really good at it. Wait - where had he learned to kiss a woman like this? And when? She'd been right beside him the whole damn time.

But her thoughts scattered as Fitz pushed her back against the wall. And never once taking his mouth from hers his kisses became deeper and more urgent. But when her head bumped the wall lightly, he stopped kissing and reached up to stroke it with his hand. "All right?" he whispered.

Jemma looked into his eyes, seeing everything she felt reflected back and she smiled. Nodding, she moved her mouth back to his, whispering, "Very, very all right."

Jemma led Fitz by an arm down the hallway on Level 3. "Where are we going?" He asked for the third time.

"There's something I want to show you." She went to the wall and opened a secret panel. Fitz jerked to a stop beside her.

"What is that?" he said as a door slid open in the wall, just wide enough for one person at a time.

Jemma stepped in them motioned for him to follow. "Come on." She said.

Fitz stepped in behind her then stopped because there was nowhere further to go. They were in a cupboard. Jemma turned around. Now face to face in the dim light of the room, Fitz reached up for the light switch but she grabbed his hand and said, "No, no light." In the quiet dark, she closed her eyes.

"Jemma?" Fitz waved a hand around. "This is a storage room."

"Yes."

"So why are we...?"

"I need your help with an experiment."

"In a closest."

"Exactly."

"OK." He shrugged, "What's the experiment?"

"I want us to -" she choked, then coughed, cleared her throat. Come on, Simmons, you have two PHDs. And this is not rocket science. "-kiss. You, I mean. I think we should kiss."

"What?" Light from cracks in the false walls bathed his features in soft blue light but she couldn't make out his expression. Perhaps she should have let him put on the light.

Taking a deep breath, she explained. "Fitz, we're scientists. Correct?"

"Correct."

"And so we both like to know how things work, yeah?"

"Yeah."

"Well, ever since my incident with the helmet we've been awkward with each other and I want to find out why."

He reached over for the light as understanding dawned on his face. "Whatever you're thinking is a bad idea." He said and turned to open the door but Simmons quickly pressed a button on her watch and the sound of a lock sliding into place echoed in the tiny room.

Without turning around, he said, "Jemma, open the door."

"I know you've thought about it but you'd never do anything to wreck our friendship - and neither would I - but I'm not sleeping because all I can think about is this thing between us."

He sighed. Then folding his arms, he turned and leant back against the door. "OK. Tell me your hypothesis."

"I think we're both curious about the other so if we were to kiss then the mystery will be answered and we can get back to being FitzSimmons."

"And that's what you want? To get back to being FitzSimmons?"

She looked uncomfortable for a moment but then she sighed. "Perhaps I've made an error. You clearly don't want to -"

"I never said that." He straightened from the door. "OK. I'm in. Have at it." Then stepped forward but he didn't touch her. "Well?" he said.

Hesitant, she moved, putting her hands on his arms but she was unable to meet his eyes she reached up and placed a soft kiss, on his forehead.

He reared back with an outraged, "Are you joking?"

"Shhhh, someone will hear you." She whispered and reached up again, this time her lips landed on his cheek and she felt the breath that shuddered from his mouth.

His arms went to her hips but she pushed them off. "Oh, sorry, I should've said. You can't do anything. I don't want to mess with the experiment's parameters."

"Parameters?"

"I get to kiss you to satisfy my curiosity then you do the same with me. Deal?"

Fitz rolled his eyes, "Deal."

"OK, so just stay still and close your eyes." Then remained stubbornly open until he saw her pleading look.

She kissed his other cheek, then rubbing her nose against it gently so she could breathe him in. She'd dreamed of these moments and she doubted that she'd ever get another chance so she planned to savour every second. Her hands on his shoulders, she felt his muscles tense with each new kiss. She was in heaven. She kissed every part of his face, but not his mouth. She noticed his breathing had changed, faster but heavier. This was exciting. No idea why she'd not thought of it years ago. Trailing kisses down his forehead to the corner of his mouth. She faltered when he breathed, "Jemma..." like he was in pain.

She smiled against his skin and moved so she was flush against him, now there was no mistaking that he was very, very aroused.

His voice, when it came, was a bit strangled, "Jemma, if you don't bloody kiss me in the next two seconds I'm going to rip off your clothes and show you what's been giving me sleepless nights."

His cheeks were flushed and he eyes were burning bright. Jemma as surprised by his words but she theorised it had to be the testosterone talking. The Fitz she knew would normally never be so forward.

"Oh, sorry, yes. I'll get on with it."

In one way she was pleased that he was responding, but, then again, most men would be the same in this situation. This was her chance to show him how she felt and he was rushing it, ruining it. She felt her stomach clench with disappointment. Clearly it wasn't about her, or them, he was just doing his bit for science. How demoralising. She felt her eyes sting.

But then she felt the warmth of his hand on her cheek as took her chin in one of his hands. Staring deep into her eyes, he said. "You really have no idea, do you?"

"Huh?"

"I want you. I think about kissing you at least forty times a day. I think about it from the moment I wake up, all day at work and then kissing you is the last thing I think of before I fall asleep most nights."

"Really?" she murmured.

He nodded. "So, now you can understand my impatience?"

In that moment, she couldn't name all the emotions she felt. Surprise. Joy. Elation. Awe. But the one that shone through above everything else was love. Proper me-before-you LOVE. She loved him. Now wasn't the right time to say it but soon.

"Screw it." He muttered and grabbed her, fusing his mouth to hers in a hungry kiss. When he pulled back Jemma stumbled a bit, her legs refusing to work normally.

His mouth quirked, "So, is your mystery solved then?"

"Ah, I think I need to spend a bit time with our findings. They're so vague and you can't base a paper on just one test so-"

Smiling, he kissed her again. But this time she was ready. She kissed him back with everything she felt. Her hands touching, caressing, every part of him she could reach. He made small sounds in his throat when she found a spot he liked. It was so strange that you could know someone inside and out and yet, in these last few minutes, she'd uncovered a new Fitz that she'd never met. She was unable to stop her own sighs and moans but it felt absolutely right to be sharing them with him.

Their kisses became increasingly urgent, neither mouth able to get enough of the other. Fitz moved her hair to one side, kissing her neck, "Leo..." she whispered.

He placed biting kisses at the base of her throat, "Yeah?"

"Your bunk or mine?"

Looking deeper into her eyes than he ever had before, he brushed the hair back on her forehead and said, "Definitely mine."