AN: Here you go! Don't worry if the coded bit is confusing, keep at it; it shows how Harry fights the Troll, but the Troll's code is... indecipherable. Good luck!

Entirely unbetad, sorry. Probably full of mistakes. :P

Chapter 22: Quarantine

The chaos was immediate; all the students knew the word 'Troll', or would within the next thirty seconds. Fear and disorder spread through the Mess and Severus resigned himself irritably to running drills over the next few weeks. He sought out his godson and Harry in the crowd, standing by the Head table he had a decent view of the tops of their heads; they were being converged upon by redheads. A fine use of the Weasley family, he supposed.

Severus followed the Headmaster through the crowd, sneering at Quirrel on the way past; the man was as useful as a blown gasket.

If the virus was in Engineering, it would be headed for the starpoint in the FTL drive - high voltages, fast moving components – and he drew up alongside Flitwick and McGonagall, in the Headmaster's wake.

"We have hours before it reaches the servers, but this evacuation is far from fast enough; organising on without gravity or Interfaces does not bear imagining." He muttered, only loud enough to be heard by his fellow Department Heads.

"I quite agree! McMurdo, hurry along!" McGonagall said, half sotto-voice and half shouted to her Prefect with his red uniform, as he led the four years of uniformed Pilots towards the door. The lieutenant nodded and harried his charges into a more efficient block. Severus' own Engineers were doing much the same, and he rewarded Flint with a nod; engineers did tend to be more... restrained than pilots.

Once they were out of the Mess, the professors – more like the Lieutenant-Colonels of their rank than teachers at that moment – filed into an elevator out of the ring and magnetized themselves to the floor as gravity faded away.

"Severus, if you would take the breakers fore of Engineering. Filius, halt ring rotation on Fawkes' mark. McGonagall, take the breakers between the servers and Control, Pommona, with me."

The moment the lift arrived in the hub, they were off in separate directions; Dumbledore heading for Control and the largest connections to Poseidon's sentient mainframe with Sprout on his heels, with coding already flowing under her fingers; Filius went for the manual breaker between the motors spinning the ring and the power conduits, a troll could accelerate ring rotation if it got its code into those motors; McGonagall followed Dumbledore to cut the rear half of the ship off digitally from the front, Poseidon's sanity must be maintained at all costs and loosing propulsion voluntarily, for a few hours, was a small price.

Severus himself was joined by the remaining teachers and Poseidon's running crew as they arrived from the far corners of the ship; Shacklebolt looked appropriately furious, while Tonks' hair was flashing rapidly through the full range of reds and blues. Diggle was understandably on edge; as Head of Engineering he would have a great deal of work to do, even if the managed to contain the virus before it destroyed the FTL drive.

Fortunately, Severus' positions as Senior Medical Officer and Lieutenant-Colonel put him firmly in charge despite Shacklebolt's nominally higher 'Colonel' rank and they followed smoothly as he stalked towards Engineering.

"How did it get on board, Shacklebolt?" he snapped. The Head of Security was supposed to prevent thing like this happening, not respond rather belatedly.

"It came in on the Package, professor; we don't know how it fitted, but it did."

Severus gave him a sharp glare; not everyone in their group had the security clearance to know about that. Kingsley just raised an eyebrow back and Severus could admit, now was probably not the time.

"We will talk about this later," he growled. "Tonks! Isolation protocol 5-7-9-2. Manual input only; so help me, if I have to pull even one of you out of Interface at this point, I will bunk you for a month."

The barely-out-of-training Captain was up to the task, but that didn't make it easy. The virus would be tearing through systems, consuming and reprogramming any processing power it could corrupt. If it started in on the systems that generated isolation protocols themselves, they would lose whole sections of Poseidon to the manual breakers. She and Kingsley hooked their belts to a terminal and begun activating the protocol, their Interfaces dark.

"Diggle! Cut off wireless transmission, I'll take the 'spike myself." Snape ordered, latching on to a console at the junction between the school sector and Engineering.

"Yes sir." The dumpy, engine-grease-smeared man vanished around a corner and the sound of opening wall panels echoed back.

A flat voice reached them over the comms; "'ring immobilised, Fawkes is logging them now."

"Copy. Starting deletion spike in five."

Severus linked in with his Interface, connecting his mind more fully to the ships systems. They were still, eerie as the marching progress of the isolation protocol shut off and disconnected processing units in offices, power distribution, Diggle's lab; the wave of quiet spread across the inside of his head relentlessly and he held himself poised, a packet of code ready to fling at the troll when it broke cover and made for the dataport in the spine.

It never came.

The entirety of Engineering, from the FTL drive to the fusion reactor went dark, and the troll never came.

"It's not here..." He broke the deep connection and hooked into communications with a frantic, messy spray of code. "It's not in Engineering. Clear the servers! GET EVERYONE OFF THE SERVERS!"

He scrambled once the message was sent, his Interface leaping off the back of his neck, leaving him feeling cut off, vulnerable but safe. Kingsley and Tonks looked up at him in frozen horror, the backs of their necks exposed and naked.

"They'll never make it in time, you know they won't!" Kingsley yelled, scrambling to finish his coding. Severus was already pushing off for the habitat ring.

Severus cursed, soaring towards the lifts and racing the progressive shutdown as Poseidon bellowed around him, angry and frustrated; the ships protocol wouldn't make it in time and with his crew rapidly vanishing off the servers, he started broadcasting over the intercom. Alarms, snippets of code, raw binary clicks; it was chaos. But, as Severus clung to a take hold in a lift travelling at double speed, the noise resolved into a string of commands;

¦u se. . user: Harry~Potter: access . denied . deniedd-d-d-deniedeni . i . ied¦

#PKT~RAKTE^DSSJ%O%IMTKCTPTHQ#

¦initiate . protocol~protego : suc-c-FAILc-cess¦

#GGATGC P~H-¦ITLZ99{DELETE}#

¦restricting . port~use r: haRrypottER : aaaacessccess . DENIED¦

#ACTN[DELETE~UNSUCCESSFUL]%79%ASSAULTP~H . #

¦CorRupuruPTIOpuuUption . deTTtTTttttected . ¦

¦user: PILOT~Fawkes: requesting . port¦

#ACTN[ASSAULT~SUCCESSFUL]ITLZ{OVERLOAD}#

¦access!granted!granted!GRANTED¦

¦INITIALIZING . DELETE . {CODE~SECTUM~CODIS}

VIRUS . PURGED . diagnostic: start . . . {processing} . . .

ALERT!user: PILOT~Fawkes: unresponsive

¦user: HHharryPo ttEr: diss-s - . {connectinging} . {connnneccted} . configggure~port¦

COMMAND: ATuser: HarryPotter: disconnect~user: PILOT

¦user: PILOT~Fawkes . disconnected¦

Severus shot out of the lift, hit the wall and pried it open to pull out the emergency kit inside. Up and down the ring, students were calling out, confused and unused to being without their Interfaces.

"Prefects! Roll-call, now!" he barked, pushing off again, kit slung over his chest. "I want eyes-on on every last first-year! Clearance: Snape, Mike Oscar." The prefects scrambled out of their harnesses as they unlocked and started swinging to check their charges visually.

In the sudden flurry of movement, there was one still pocket, where all eyes were fixed on the shining red and gold of Fawkes' feathered head.

The pilot was slumped loosely in Harry's grip; one tiny white hand held the back of his head and the other clutching his Interface. Smoke drifted in uncanny, bluish grey coils from between Fawkes' feathers. Harry's eyes were wide, staring fixedly into nothing at all but his mouth moved slowly.

"You too, Mr. Weasley; look to your duty." Severus clipped himself next to Harry and the Prefect shook himself and went to a crying first year. "Orion's Beard, Fawkes, what have you done to yourself..." he muttered, prising Harry's hand off the pilots' Interface and giving the shock-cold fingers a brief, comforting squeeze. He hastily tucked the smoking tech into a pocket with his other hand, ignoring the smell of burnt plastic and feathers, and leaned in close to check Fawkes' breathing. At that distance, Harry's mutterings were audible, and heartbreakingly soft:

"It's ok, Fawkes, shh... you're ok... Poseidon says... well done. Shhh, shh..." a child's whisper, full of adrenalin and fear and wonder and the size of the universe.

Fawkes' eyes were open and looking at nothing, his temple resting on Harry's collarbone, but he was breathing. Harsh gasps, full of pain they may have been, but he was alive. He flipped Harry's wrist and tucked the fingers of his other hand into Fawkes' carotid to check their pulses; they were both heading rapidly into shock, but their hearts were still going strong, despite the massive electrical charge the troll had thrown at them.

Severus squeezed Harry's hand again before laying it on Fawkes' shoulder and twisted to brush the feathers away from the back of Fawkes' neck. He was already reaching for a burn sealant and his guess was on the mark; where the pilot's Interface had sat, his skin had burned to a shiny, bloody pink, edged in the crisp black of burnt feathers. It disappeared under the bright orange salve, sealed, disinfected and numbed in one swift gesture.

Fawkes shuddered and let out a long breath, his eyes closing and his grip on Harry's harness going abruptly loose.

"Alright... Harry? Look at me, Mr. Potter." It took him a while, but Harry's eyes focused eventually. "Let Poseidon hold on to you for a little longer, Harry. He doesn't want you to be afraid, he's just keeping watch over Fawkes. Do you understand?"

Harry nodded slowly, his eyes drifting down to look at Fawkes.

"Good. !" Severus called the Prefect over, "what are our orders, cadet?"

"Admiral D-D-Dumbledore has called the all clear, sir, we're not to Interface and should put out rooms in lockdown."

"Very good, see to it. I'll be taking Fawkes and Potter to the medical bay; see that the roster is changed."

"Yes sir!"

With communications on hold and Poseidon missing half his systems, the ring was chaotic at best but teachers were beginning to filter in from their emergency posts and take command of the Prefects. McGonagall's voice from the second year section was particularly audible. With Fawkes down for the count, deep in shock, the first years were being wrangled by Prefects alone. They were afraid. Stressed and hysterical, and Severus did not have time for forty terrified children.

And then Harry started humming.

He wasn't particularly tuneful, or loud, but the little hiccupping noises sung into Fawkes' feathers were utterly familiar; Holst's 'The Planets' and the strong, lilting tones of 'Jupiter: bringer of Jollity', a twelve hundred year old piece of music.

It was Poseidon's favourite, had been since he'd been decommissioned from a battle cruiser into a school after the Unity War, the very birth of Spacer kind. Over a thousand years ago.

Harry couldn't have heard it before.

You can't cry without gravity, but, looking at Harry's pale face, his little hands cradling the pilot close...

Quiet spread slowly amongst the first years and the Prefects plucked them out of their harnesses one by one. Severus did the same, unbuckling Harry and wrapping the pair in a shock blanket from his kit. Fawkes sighed and settled quietly with his arms tucked around the humming little boy.

Severus couldn't speak, couldn't think, but procedure he'd followed since before Harry was born carried them through the thinning crowds all the way to the ringside medical bay. Pomfrey met them and helped him guide the pair to a bed, tucked in tight to stop them drifting away.

"He's a Greatship Pilot, Poppy..." Severus mumbled, managing to stress the capital; the adrenalin in his system was crashing rapidly and he chewed numbly on the square of chocolate Pomfrey pressed into his hand.

"Well of course he's a Pilot, who'd you imagine was flying this old ship?"

She didn't get it... Severus gripped her shoulder as she bustled past with her case. "Not Fawkes, Harry."

"Don't be silly now, Severus, you've got patients to see to, you can't go into shock yourself."

He shook his head, making an effort to pull himself together and hooking his feet under the floor bar by the bed. "I'm serious, Poppy, half of Poseidon is flowing through his head right now! How else would he sing that?!"

The nurse gave him the long look he remembered from his own schooling, and then looked down at Harry and Fawkes, wrapped up together with the entire ship looming over them.

"Well... Good luck keeping that under your hat for seven years." The nurse jammed her own cap on her head and closed the door behind her, shutting him in with Harry's humming.