A/N: It's Stargate Sunday again! We're officially past the halfway point, and everything is fine. Yup. Just fine. No, really. Casey's fine. Sheppard's always fine.

Lorne is not fine.

In this chapter: Casey doesn't breath. Sheppard breathes too much. Beckett is flustered. Lorne glares. Oh, and the city might be eaten by bugs. Everything is just fine.

Spīrāre (Noun and Verb, present infinitive of Spīrō [spi-ra-reh]): a breath; inhalation; to draw in a breath; to respire; to breath.

Four and a half weeks after The Incident, as she's taken to calling it, Casey is down in one of the new Level 4 labs trying to figure out how they can set up and cycle the nutrient feed lines most effectively between a series of large, immovable aquaculture tanks when suddenly Sheppard is there.

In the room.

With her.

Alone in the room with her.

She tries her hardest not to panic, and is mostly successful only because Sheppard isn't blue any more. He looks like a normal human again... And he isn't touching her. He keeps his distance, and she keeps her calm. Mostly.

Maybe.

He's trying to say something, but it isn't working very well. There's a lot of shuffling, hands in his pockets, and scuffing at an invisible spot on the floor with his shoe, and rubbing at the back of his neck, and she thinks he's saying words in her general direction. Maybe it's her ears that aren't working well. She's not sure. She has to remember how to breathe, first.

He's wearing jeans and a blue shirt. He looks... normal. She manages a breath, and then another, and gradually the panic subsides just enough for the tight band across her chest to loosen. Sheppard has stopped speaking and is looking at her with an expression that's alternating between concern and guilt. He can tell he's making her uncomfortable, has made her panic. He takes a hesitant half-twist-step backwards, and he looks like he's about to bolt. She has no problem with him leaving. Really. Please please please go away her mind is quietly screaming. Calm down, he's himself again, he won't hurt you her brain is saying rationally.

He takes a deep breath, somewhat resignedly, and another half a step back... and stops. An odd look she can't decipher crosses his face, and he turns to stare straight at her.

She stares back. Five long, rapid strides later Sheppard has crossed the lab; he steps right up to her, eyes still locked with hers, and... sniffs at her.

They're both surprised by that, and just stare at each other uncomprehendingly until Sheppard deliberately leans forward, closes his eyes, and breathes her in. He pulls back, startled, and Casey is back to being frozen again. His eyes jerk back to hers, and he blurts out the words that make immediate sense to her.

"You smell... pregnant."

It's becoming harder to maintain his calm façade as he checks the main Xeno lab and there's still no sign of Casey.

Damn it.

He has to find her, and quickly. Unobtrusively. He strides purposefully down to the lab on the level below. It's empty.

Crap.

Maybe one of the other Xeno team can tell him where she's supposed to be. He heads back up to the lab to where Dr Ellingson is staring at something under a microscope.

"Hey Doc," he keeps his tone casual. Ellingson swivels around and grins widely at seeing him.

"Major! Come take a look at this! We've discovered a complex aquatic extremophilic organism which appears to have the ability to eat metal! It's incredible! You have to see this!" He waves a furious hand at the equipment spread out before him on the lab table.

"I was actually just wondering if you..." Wait. What? That doesn't sound safe.

"What do you mean, 'eat metal'?" he asks, warily.

Atlantis is made of metal, and floats on the ocean. Things that eat metal and live in the water would be bad. Very bad.

"It's similar in size and appearance to a Tardigrade, except for the ability to eat metal. Well, not so much eat as... assimilate and convert metallic compounds into other molecular forms depending on the pH level of the basal fluid! It's amazing, really! Did you know that Tardigrades can survive extreme heat, cold and radiation? And even the vacuum of space? I'd venture these little metallophagii have similar resistances. Remarkable!" The excited xenobiologist rattled off as he plastered his eyes back to the microscope in front of him.

Lorne blinked. Yeah. Metal-eating indestructible water-based organisms. Who the hell authorised bringing these samples to Atlantis? It's a serious risk to the safety of the city, and as acting Military Commander in Sheppard's absence, he'll have to take it up with McKay, make sure they've got proper containment protocols in place to prevent... No. Wait. Sheppard. Casey. Focus!

"Do you know where Doctor Cartwright is working today?" he asks with a calm he's definitely not feeling on the inside. He can worry about Atlantis being eaten by invincible waterbugs later.

"Hmm?.. Oh, yes, umm... She's on the.. err.. nutrient feed line project. Umm..." Ellingson doesn't look away from his scope. "The Aquaculture team is trying out a new bacterial-based closed-loop hydroponics system... trying to establish a symbiotically enhanced growth cycle between the sea-spinach-root from Indarhama and those squidfish things from P7M-841!"

Lorne has to fight not to roll his eyes as Ellingson segues again, without telling him what he wants to know.

"And where is the..."

Lorne is interrupted by a triple chirp from his radio.

There's nothing but silence in the lab, and Sheppard looks stunned at his own outburst.

She feels… remarkably calm, considering. 15 seconds earlier he had been across the room and she had been frozen in fear, unable to breathe. Now he's standing right there in her personal space, close enough to reach out and touch, and all she can think is that it's fascinating, really, that Sheppard can still scent her, after all this time.

Pregnant?

Pregnant... she has felt rather odd for the past three weeks, but she had been unable to put her finger on what exactly was wrong, and had just attributed it to her body slowly healing all over. Most of the bruises are completely gone, and the last smattering of stitches had been taken out the previous week... but.. pregnant.

So many things made sense now.

Pregnant.

Sheppard is still right in front of her, staring at her like a frozen deer in headlights. Casey lifts her hand to her headset, and the motion seems to awaken him to the fact that he's standing less than a foot away from her because he promptly backs off to a more reasonable distance as quickly as he had arrived.

"Control Room, this is Dr Cartwright, come in please?" her voice is steady and neutral, and Sheppard looks momentarily panicked.

"This is control, go ahead Dr Cartwright." the friendly technician's voice chirps professionally in her ear.

"Could you please connect me to Major Lorne on a private channel?" She doesn't want to hail the Major on an open line. Fortunately, private channel requests are allowed via control. Sheppard has been slowly backing towards the open doorway, but at hearing who and what she requests, he stops. There's the distinctive triple click that indicates the transfer is being connected, and moments later another triple click precedes the opening of the channel.

"This is Lorne, go ahead."

"Major, it's Dr Cartwright." Casey keeps it professional even though it's a private channel. "Are you busy right now?"

"I was actually just looking for you, Doc." Lorne's tone is close to neutral, but there's an edge to it that she can't quite decipher.

"I'm working in one of the new Level Four Aquaculture labs," she answers his unasked question, "but I was wondering if you could meet me in the Infirmary in... ten minutes?"

"Absolutely, Doc." Lorne's response is immediate. "I'll be there in ten." His tone is still neutral, but his clip betrays the worry in his voice.

"Thank you, Major." she tries to reassure him that she's not in immediate danger. She ends the connection. Sheppard is still hovering just inside the doorway, just watching her. She taps her radio again.

"Doctor Cartwright to Doctor Beckett, come in please?" Calls directed to Beckett are initially public, but as soon as he picks up the call it automatically switches to a private channel. It's a confidentiality protocol, one that she's extremely grateful for. The radio clicks three times and the Scottish doctor's brogue fills her ear.

"Aye lass, what can I do fer ye?"

"Doctor Beckett, I need to see you. Are you available in about ten minutes? It shouldn't take long but it is rather urgent." She has a bit of a plaintive tone, but she has to see Carson and she has to see him as soon as possible.

"I'm in mah office, love, I'll be here waiting." Good, okay, that's good. She's got Lorne, and she's got Beckett. Two down, one to... go. Away, preferably. But she has to ask, especially since as soon as she reports this to Beckett he's going to call the Colonel in anyway. She's pretty sure Sheppard isn't supposed to still be able to smell things. He's back to human, right? Focus. Breathe.

Sheppard watches her as she walks towards him. He still looks like he's not sure whether he wants to flee or... well, not flee. He doesn't move though, and lets her approach him.

"Would you prefer it if I did this alone?" she asks quietly. He has to have the choice. She didn't, and he was as much a victim as she was. It's important that they have choice, now. He considers her words with a grimace, and then, surprisingly, shakes his head.

"No." he says, hoarsely. "I need to... "

She simply waits, quietly, as he trails off and struggles to find words.

"No." he eventually repeats, and that's that.

She takes a deep breath, and nods at him, then gestures for him to precede her.

They walk to the infirmary in silence.

Lorne makes it to the Infirmary in 7 long minutes, walking at a leisurely but purposeful pace to avoid drawing unwanted attention. He heads straight through to Beckett's office. Casey didn't specify where, but if she's coming in then she's likely heading to see Carson. The Scottish doctor blinks up at him when he appears in the doorway.

"Casey asked me to meet her here." he explains in lieu of a greeting.

"Ah" is all he gets in response. There's no need for small talk or polite niceties between them, especially when it comes to Casey. The events of the past few weeks have led to both of them developing quite the protective streak regarding the seemingly eternally cheerful and optimistic Xenobiologist. Well, Beckett tended to get that way with all his patients, and Lorne had the security and well-being of everyone in Atlantis in his purview as military XO... but this was different. This was Casey... and Sheppard, and the retrovirus, and horrible events that had resulted from failures on both his and Carson's parts.

He settles himself against a lab bench at the far end of the office. He's apprehensive and worried, but to the casual observer he would appear casual and relaxed. He's picked up a few things from Sheppard in the last few months, one of them being how to look like he's more relaxed than he really is. Sheppard has it down to an art form, though, melting languidly into chairs and against walls as though he were perpetually bored or on vacation.

Movement at the door draws his attention, and he has to call on his best poker face to hide his surprise when Sheppard steps into the office. The Colonel only gives him a momentary glance before looking away. Lorne doesn't. He can't. His eyes are locked on Sheppard, who is studiously avoiding looking back at his glaring XO.

Casey steps in right behind Sheppard.

Uh oh.

It seems Sheppard managed to find her first after all. Sometimes his CO could be an impulsive asshat. Lorne had tried to stop him, had told him that the last thing he should do was confront Casey, but the man clearly hadn't seen reason. He'd gone straight for her, and now they were meeting in the Infirmary. His stomach is turning cold. What the hell did you do, Sir?

Beckett is also giving the Sheppard-Cartwright combination a wary look, and he shoots Lorne a warning glance as Casey waves her hand over the sensor to close the door behind them. Sheppard appears to be attempting to merge with the wall in the corner of the room, and Casey ignores him and steps right up to Beckett.

"What's up, love?" Carson switches to doctor mode immediately.

Casey takes a deep breath, and casts a sideways glance at the Colonel. He crosses his arms over his chest, and stands up a little straighter. Lorne eyes him suspiciously. Something odd is going on here.

"I need you to do a pregnancy test."

Lorne's stomach turns to ice.

Casey tries not to look down as Beckett fiddles with the phlebotomy kit.

It has nothing to do with the blood sample the doctor is taking from her right arm, and everything to do with the fact that Sheppard is holding her hand. He had incrementally hovered closer and closer to her as Beckett had prepared for the draw. When Beckett turned back with the needle in his gloved hand, Sheppard had simply reached out and gripped her hand. Behind them, Lorne had made a choked sound, quickly followed up by a cough. She wasn't panicking. She wasn't, really. Instead, she desperately tries to profile, to find some reasoning or justification for everything that happened in the last 20-odd minutes. Unfortunately, Casey knows animals, not humans. Human behaviour is a whole different kettle of fish. Or, she wishes it was, because fish she could probably understand too. But people? And not just any people, but specifically Colonel Sheppard, the eternal enigma?

She can't profile him. She's distracted, anyway, by the hand gripping her own as Beckett takes the sample. His hands are cool, but not cold or clammy. His fingers are long and lean. Nothing like Major Lorne's warm, solid hands. It's awkward as hell, but he doesn't seem inclined to let go, so she leaves it alone and focuses on just taking the next breath. Beckett pats her on the arm briefly before he disappears out of the office to process the samples.

Lorne stays, thankfully, settling himself back against the table off to the side. He alternates between eyeing her, eyeing Sheppard, and frowning at their joined hands. Silence reigns. Casey just keeps focusing on a spot on the wall above the doctor's desk.

Beckett is back less than five minutes later, looking a little flustered. He simply nods, and gives it a few seconds for the news to sink in.

"What would ye like tae do, love?"

TBC!

Good news everyone! This chapter exploded so much (1,100 words to 4,500) that I ended up breaking it into two parts (2,600 and the other around 1,900). More story for you, but also more waiting! *evil laughter* Instinct will thus have 14 chapters in total. I'm pretty sure none of the other chapters will explode, since there's much talky-talky coming up from Chapter 10 onwards. Again, since so much of this evolved between being opened for edit (11pm) and hitting save the last time (4am) there might be mistakes. PMs with errors are appreciated! (As are reviews. I love reviews. Reviews are like oxygen, feeding my fanfiction fire. Yay reviews!)