This is a crossover that I've been wanting to write for weeks. A teaser and a prologue here, I know, but I wanted to test the waters...

House was easily bored, rarely intrigued and even more rarely impressed. As he read through the file that Cuddy had laid with unusual ceremony on his desk for the fifth time, he found himself gravitating exclusively to the last.

Top Secret had captured his attention, particularly.

Tossing the file with a spin from his wrist back onto the desk, he sat back and picked up the largest of the softballs to hand with the tips of his fingers. Flexing his hand, he brought it up and down in time with his pulse as he stared at some point between himself and the ceiling. He'd been asked for by name for this case (hardly a first), and had been sworn to secrecy before Cuddy had handed him the file. Given the steely control on her trepidation, he concluded that she'd had to sign a similar waver before putting his before him, and had handed said signed form back to a mysterious man in black minutes after leaving the office.

The symptoms in themselves weren't at all that interesting – any first year medical student would have concluded that the patient had pneumonia. But then, most patients weren't alien mechanical life forms. That somewhat changed the presented symptoms.

Cuddy had levelled her hips and arched her brow when she'd told him that the military were looking to make a 'big investment' in the Princeton Plainsboro Teaching Hospital if he could make any headway, which meant a particularly big investment and that he should make his department worth the amount they cost. Hell, House had decided with a twirl of his cane, he'd look at an anthropomorphised monster truck for free, but if the military insisted on paying then that was fine too.

There was a number at the bottom of the summary of findings so far, long after the disclosure warnings and insinuations that he would be shot for talking to anyone who hadn't been authorised about the contents of this file. Even if he'd decided to turn down the case, House knew that he'd have still called that number out of curiosity alone.

It didn't ring; there was only a thick silence before a very terrestrial sounding voice asked, "What?"

He'd long memorised the file, and House swung in his chair to set his feet up on the desk and speak to the ceiling. "Doctor Gregory House, answering the bat wave. Is this really about a giant robot? Seriously? Or is that part of a delusional symptom I should know about up front?"

"Four 'giant robots' to be precise, Doctor," the gravelled voice drawled back. "Am I to assume that your calling this number means that you're taking the case?"

House squinted hard enough to crinkle his nose, swinging in the chair at a speed and distance that didn't hurt. "Depends. Are you guys really aliens?"

A beat as the other speaker on the phone hesitated, before finally: "Yes."

House grinned. "Cool."

Though the voice didn't seem to breath, there was certainly a sighing sound to be found in the next pause. "My designation is Ratchet – I'm the Autobot's chief medic. These symptoms are presenting in four of my unit, including our Commander, and it seems more a biological syndrome than a mechanical."

"Hence getting a consult from a biological," House concluded, setting the ball that he'd been using as a prop to think with back onto the table. Minimising the game of Solitaire that he'd been playing before Cuddy had arrived, he began checking his schedule for the next few weeks. "'Ratchet's a noun, by the way, not a name."

"So's 'House', but I won't hold it against you," Ratchet replied flatly. He didn't give the man time to respond, speaking as if this conversation was occurring within a very limited window of time. "NEST personnel will bring you to Diego Garcia to make a preliminary assessment, as our patients are far too conspicuous to be brought to your hospital. You're authorised to bring anyone you require, and I'll be present to provide you with as much information as you need to solve this."

House slid his feet down from the desk and spun the chair further, now facing the windows and looking up at the gap between the blind and the ceiling. "I wouldn't promise that if I were you – I can be quite needy."

A grunt of a laugh, humourless and entirely tolerating for the sake of professionalism. Rartchet's tone remained unchanged. "All four patients have excessive and unexplained fluids in their vents, dramatically debilitating their coolant systems. As a species we're used to adapting our systems in minor ways to better suit the environment we are living within, which has always been transient. This is the longest we've remained on a planet with atmosphere and life forms, thus the longest opportunity our species has had to mutate since we left our home world. And this is the first time there have been such detrimental side effects."

"And you think 'nurture's got it wrong," House remarked to the ceiling tiles, the back of his mind trying to imagine what the creature he was speaking to looked like. It was eloquent, male and well informed – he would have taken Ratchet for human if it weren't for all the red stamps and mentions of 'alien' in the folder. If anything he just had to see these guys, irrespective of whether he could help. "Alright. I'll have the gang ready to slip into some of those figure-flattering orange tracksuits and we'll see what we can do."

Ratchet hummed a low sound that seemed to reverberate in the bottom of House's stomach. "I'll have the patients ready for samples to be taken, and you'll have their full co-operation."

That tone, House decided, was very like his father's had been – with an underlying sense that he had weaponry and wasn't averse to using it. Not a threat per say, nor an excess of confidence, but a knowing trust in a means to cajole and threaten. Still. "I can't promise anything. I'd have just as much luck treating one of those green chicks off of Star Trek as this."

Ratchet's smile was audible, and even then far from reassuring. "Don't worry, Doctor House – the histories that I give you shall be nothing less than comprehensive."