This is less than I wanted but it's taking a while so here is something better than nothing.
As ever, standard disclaimers apply.
"Yeah, I felt something." Shacklebolt's wary expression did not inspire confidence. "I can't say it felt like magic, though, Severus. You're sure it's the same as what you felt beneath Stonehenge?"
"Yes. But stronger. It felt as if... as if the whole of existence was being twisted inside out." He frowned at his own rough words, fully dissatisfied with them. They were the best he could come up with, however, and he did not believe that any words existed to truly describe what had torn through him. He felt a series of soft pats on his arm and looked up to see the owner of the other concerned face. Apparently the gesture was meant to be comforting, but he felt none.
She mumbled something neither wizard had any hope of understanding and then busied herself cleaning up after Severus' unfortunate reaction. Others as well began to stir and release themselves from the harnesses that had kept them all from being flung about during the attack. A few stayed where they were, apparently having nothing more to do than rest. Someone tended to their still limp comrade. Subdued conversation resumed.
"I suspect we've outrun our pursuers," Shacklebolt mused aloud.
"Yes." Severus frowned as his gaze locked onto what appeared to be some kind of magical window. "What is that?"
The Auror automatically turned to look at the viewscreen and his response died on his lips. "Oh." Space had changed. Where once there had been a velvet black studded with point-like stars, there now was a sort of brownish grey haze of undecipherable composition punctuated by only an occasional faint glitter. "It did show space outside the ship. Now, I don't know what we are seeing."
"An enchanted window?" Severus mused. His throat was raw and his voice was giving out.
The other wizard shook his head. "This lot are as much Muggle as the last. But that is not what space looks like."
"Then we are elsewhere." Severus voiced the only reasonable conclusion.
"Can't be. There's still no gravity."
"We are seeing something not real, perhaps."
"That must be it."
The two terrestrial wizards stared silently at the window, but the image varied only minutely. The activity of the floating, swimming crew was far more interesting if equally mysterious. Those few moving about did so with practiced ease and generally a fair bit of grace. Mostly it seemed they were repacking hastily stowed gear. One woman who apparently acted as a medic had finished with the still unconscious man and was examining the woman who'd been unlucky enough to be grazed by whatever the weapons fired.
The concerned woman returned carrying a bulb shaped container. She pantomimed drinking from the slender pointed end then held it out and indicated Severus with her chin. She patted her stomach.
The disembodied voice spoke again and the activity became hurried for a moment as they all seemed suddenly to need to rush to finish and re-secure themselves, and one of them curtly gestured for Kingsley to do the same. The Auror chuckled. "How's your stomach, mate? I think she's worried you'll sick up again."
"I doubt there's anything left," Severus grumbled faintly.
"How are you feeling, then?"
"It is like Stonehenge. But slightly different... As if the magic flared and was quelled."
The woman gestured again, this time with words accompanying and her features somewhat anxious.
"I'll drink it," Severus decided before Shacklebolt could argue with her.
"You sure?"
"It cannot possibly be worse than feeing the whole of existence twist itself inside out." He held out a hand and the woman delicately placed the container in his palm, again gesturing that he should drink. He obeyed. Then gagged as a sticky, cloying substance coated his mouth and slid down his throat. He let go of the bulb but it only floated gently where it had been released. He coughed and choked and was distantly aware of his companion frantically calling his name. He choked again when he tried to answer, but he waved a hand to signal that he was not dying. Finally he gasped and opened his eyes. "If it's poison, I hope it's fast," he gasped to the worried dark face peering concernedly at him.
"How's your stomach?" The Auror's voice was all tense concern.
"Fine." Severus closed his eyes. "Tired," he murmured. Then forced his eyes open. He felt himself smile. "Fine," he repeated his original assertion with an unintentional soft, silky slur. Indeed he did feel fine. He'd never felt so fine. As if he Understood. As if he and the whole of the universe were One. Now, as he looked at the window and let it capture his gaze, he Understood that what he saw was but a weak analogy of reality. He turned his gaze to the older wizard, now settled in a harness nearby. He took a breath and reveled in the sensation of Old Magic coursing through him. He parted his lips and inhaled as some words formed from his thoughts--
Again the universe flipped itself inside out. Again the flare of Old Magic overwhelmed his senses and while it again caused great dizziness, his stomach did not, this time, attempt to surge up his throat and out his mouth. A deep sound resonated from somewhere within his chest and he realized that he was groaning. He quieted himself and was then able to discern Shaklebolt's voice once more calling his name. He looked up, his eyes searching and quickly finding the other wizard fastened to the bulkhead. "I am well," he said not even sure he'd been asked.
"Look at the window, Severus."
He obeyed. The flat dark background and its myriad pricks of light had returned.
"Still feeling Old Magic?"
Severus nodded slowly. Yes, it was there, an undercurrent of something indescribable. But somehow changed. Somehow, and he didn't understand how he could tell how, he recognized it as being very much like what he'd sensed below the famous henge. Before he could say anything about his perceptions, the disembodied voice made some announcement that had everyone cheering.
"We must be 'home.'" Kingsley opined wryly.
A moment later, the inexorable presence of the gravity of a nearby large mass began to pull and thereby define 'downwards.' The window unhelpfully showed only star speckled space.
The pull quickly became onerous as an invisible pressure squeezed his lungs so much so that Severus was uncertain that he could draw in his next breath. Just within his suddenly contracting vision he saw a look of pained horror on the Auror's face that he was sure matched his own.
And then his ears popped and the pressure disappeared. No. Not quite. It was still there, a singular tightness and heaviness that was not at all familiar.
"Merlin's beard, that's torture." Shacklebolt's voice was unusually - but not unaccountably - shaky. "I don't know how these Muggles put up with it." But their alien companions seemed unperturbed by the experience.
"It's not right yet," Severus remarked more to himself than to his companion. he watched as the Auror was released from the restraints and supported on his feet as if he might fall. Severus was released but immediately lifted over the crewman's shoulder again. This undignified position annoyed him but he decided that the alternative -- crawling pathetically -- was even less desirable. He couldn't see how Shacklebolt was managing but he did hear the larger wizard grumble softly once or twice.
Severus remained quiet, observing from his inverted station the disembarkation from small spaceship to much larger hangar. Other alien Muggles emerged from doors heading to positions about other spaceships to, apparently, resume whatever tasks the arrival of their ship had interrupted. Occasional shouts passed back and forth. Then they passed through one of the inner doors and into an over-lit, undecorated, dully colored hallway. He winced and squeezed his eyes shut for a moment before forcing himself to squint through his eyelashes.
"All right, Severus?" Shacklebolt's deep voice asked from nearby and he felt the Auror's hand press against his back.
"Fine. Just too bright," he assured the other wizard. Their captors or hosts (which would depend on their treatment of course but he wasn't expecting laurels and a free trip back home) didn't seem to mind the two conversing. Either they were overconfident or it did not, in fact, matter.
"Yeah," a gruff chuckle agreed shortly.
After several long minutes of nothing but the rhythmic hiking the party finally came to a stop. A circular door rolled open and they finally entered another room. Severus felt the world tip as he was righted and set down into an overlarge chair. Shacklebolt slid into the chair beside it. They were seated at a large oval table that was hollow in the middle where a bank of panels faced out at all around. The whole table was ringed by these large chairs into which the rest of their companions, save the two wounded members, were busily settling themselves. At what could only be the head of the table a woman sat already. She was no more in uniform than anyone else, but there was no mistaking her as anything but in charge of this gathering.
Both wizards were very aware of her stare upon them as she waited for the noise to settle down.
"Gentlemen, welcome." That's not what she said. But it was what came out of the round edged box sitting on the table at her right hand.
The two wizards shared a wary look.
"We know what you are. And your presence puts us on almost footing with... others." She had the good grace not to smile.
"We just want to go home," Kingsley replied without trying to be either polite or rude. If he sounded weary, all the better.
"Would that I could deliver you there. But I can't."
Shacklebolt muttered something very rude. The box squawked and the female glared. "That did not translate but I have no doubt it was an expression of dismay," she replied.
"Too right it was," Severus hissed back. "What do you want with us?"
"We want to know what you know."
Before Severus could even formulate a reply the Auror's unamused guffaw rang through the room.