"Haemothorax on the left, mediastinum widened – why the hell is she still on cyclical? Who's gonna be scraping bits of her from all over the place? 'Cause I'm not volunteerin'."

Spock watched from the neighboring biobed as the doctor quickly changed the resuscitation pattern on the patient and went to pull his gloves on. This other McCoy did appear somewhat confused and unsteady on his legs while he was being escorted to the sickbay. As the doctor's gaze wandered bemusedly, Spock was asking himself if he had by any means deserved his nickname. The original McCoy's appellative was derived from the same word – 'sawbones'. But while 'Bones' sounded somewhat harmless, the full form gave the doctor from the other side of the mirror an air of degradation.

But while Spock watched the other one start the operation, he concluded that the nickname was, by and large, a misnomer. At work, the mirrored reflection and the prototype were one and the same man.

"Scalpel. And rib spreaders, in situ."

Doctor McCoy made an incision, and the familiar metallic smell of blood hit his nostrils. Something clicked inside his irreversibly damaged consciousness. Something that was, perhaps, too down-to-earth and unsophisticated for mirror-Spock to even put his finger on. He wasn't sure what it was, but it suddenly sprang to function, just as ever. Now that he was seeing the sight he was so used to – a prostrated body that he just cut open – the knotted ball of torn circuitry inside his brain untangled itself. His thoughts ran in perfect order. His mind was clear.

He pried the woman's naked ribs open, secured them with the retractors, and dug his gloved hands into her chest cavity. There. McCoy's fingers reached the fractured aortic walls and began protoplasting them back together, the delicate sensorimotor activity sharpening his instincts razor-thin. He did it, with the nurse passing the instruments and mopping. Doctor M'Benga was playing it cool but still enchanted at the sight. He did it, not a drop of sweat, not a single slip. He performed flawlessly, although he'd never done it at phaser-point before.

"Bone- and skin-knitter."

The doctor closed the woman's ribs, knitted the bone tissue together with an osteoregenerator, and ran a dermal regeneration device over the cut. He then pulled the blood-stained gloves off and stood there, observing the patient in her sleep. Spock rose from his place and searched the other McCoy's face. There were the subtlest shifts in the facial expression, and how the other McCoy's shoulders drooped, and some other imperceptible changes that removed the illusionary original and materialized the mirrored doctor back into his own self. Fascinating.

Doctor M'Benga shook his hand, sternly but amazedly. Christine touched his shoulder, softly. The danger has passed, everyone was happy, and the girl would probably live to tell how she was operated on by a mirrored man.

"Time to return," Spock noted, after everyone said their thanks.

The tired doctor seemed to shrink in size at the sound of his words. He touched the purpling bruise on his forehead and looked confusedly about. Spock's phaser followed doctor McCoy's trajectory as he walked noiselessly around the ward – like a beaten dog.

"Can we drop in to my, uhh, his quarters on our way?" he blurted suddenly, "Just curious, y'know."

"I understand your unwillingness to return to the company that harasses you, but we are very short of time."

"Ya, sure. Just thought it was a once-in-a-lifetime opportunity, is all," the doctor said, surveying the sterility he wasn't quite used to.

As they walked through his cabinet on their way to the exit, he slowed again, amused at the cleanness of his counterpart's workplace. Not a bottle in sight, not an empty re-used hypo, not a scrap of rubbish anywhere, nothing. His gaze clouded suddenly, as a thought flowed over him.

"I wonder," he said, softly, "If he also keeps the picture of his poor little daughter up there, in that left drawer."

"Poor little – ?" Christine asked, puzzled, "But Joanna must be in her twenties by now, safe and well at Cerberus school."

The doctor's face went blank. He kept silent for a while, brushing his hand across the tabletop.

"Some lucky bastard of a father he is, then," he said, studying the tabletop intently, "My little girl never made it to the school. Died of leukemia, age seven."

He shot a momentary glance upwards to check the reaction. Was his trick too crude, too obvious? Back at home, he'd get the hell to pay for this bullshit the moment he'd think it – but no, not here. Absurdly enough, his poorly-fabricated lie produced just the response he'd hoped for. Pity. It was there, at the bottom of everyone's eyes, including Spock's. Doctor McCoy almost let out a chuckle but knew better than that.

Spock observed the doctor is his anguish, and sensed compassion churning up from the inside. He geared his inner mechanisms to empower thought over feeling. A deep noiseless breath so that no one noticed. Acknowledge, label, accept, dismiss as immaterial. Analyze. The doctor did perform the operation excellently. Shoving him, a forlorn father, inside the brig and leaving him for the others to bully would be ungrateful. Gratitude was a human concept, and a very important one for the original McCoy, in all his humanness. Perhaps, the other's mood would also improve after he felt his efforts were acknowledged. A relaxed and cooperative mirror-McCoy was preferable, considering that the time (or the very fact) of the original McCoy's return was uncertain.

"We shall visit the doctor's quarters," Spock said, levelly, "I urge you, however, to be as brief as possible."

As they walked along the corridor and into the turbolift, the doctor was doing the talking. He told Spock a little about his daughter, and how he mourned the loss, and how he divorced his wife, alienated, and joined the fleet. Spock listened and observed as he spoke. This McCoy's vowel-drawling was more apparent, which made him sound somewhat uneducated. There was a subtle difference in the complexion color (paler, grayish) and body mass (he was thinner). But otherwise, the mirror-McCoy looked and behaved quite decently. Quite like the original one, in fact.

"What are you, eyeballing me or what?"

"Merely studying," Spock said, still thinking.

The doctor laughed a short laugh.

"Honest as ever, huh. Guess that's how it goes: when the whole universe is mirrored, there's one thing that remains unchanged. Our trust."

They entered the doctor's quarters, and the other McCoy took a good look around. Clean. He opened a drawer just for the show, and found no pictures in it. He then walked over to the cupboard where he'd kept his booze back at the I.S.S. Enterprise, and opened it. The shelves were half-empty. Or half-full, depending on how you saw it.

He picked a bottle of what looked like black rum, poured himself a shot and took a swig. Good stuff. He paced around the room, the shot in his hand, his throat tingling pleasantly. He was about to drift into a flood of remembrance, when he suddenly realized the Vulcan was still there, watching him, stone-faced but impatient. By golly, he'd almost forgotten all about him. That's what mind-melding does to you, all right.

The doctor poured a second shot and offered it to Spock. The Vulcan shook his head.

"If you are finished, we had better go back to the brig. I will proceed with my work so that you and your companions could be safely returned."

Back? Back to the stench, the insults, the mind rapes, the madness? Doctor McCoy didn't think so. His thin lips curved into a sickly smile, visibly, as he slouched in a chair, legs crossed.

"Guess I'm gonna be just as comfy in here, thank you very much."

Spock kept silent for a moment, quite stunned. He had anticipated such a possibility, of course, and yet the treason struck him with its blatancy.

"You are betraying the very trust you said was unchallenged across the universes," he said, coolly, "Your staying here is out of the question. Please do not detain us any further."

McCoy smiled wider, finished the shot, and took the one that was meant for Spock.

"I'm not goin' anywhere. Not now."

"I should not like to apply force, doctor," Spock said, moving forward, "But if you leave me no alternative – "

The Vulcan made another step, and the doctor sprang to his feet. He grabbed the rum bottle by the neck and smashed it against the tabletop. The glass shattered into pieces, spilling the liquor, and leaving doctor McCoy with a sharp bottleneck in his hand. He stabbed the air in Spock's direction.

"I said, I ain't goin' anywhere!" he snarled, dog-like, his teeth bare, "What are you, fuckin' deaf with ears like that?"

Spock sighed and went closer. He could phaser-stun him, but chose not to: the doctor could cut himself on the glass when he fell to the floor. The Vulcan had five times the doctor's strength, and although he would rather not use physical force even on that wicked creature, he was left with no choice. He caught McCoy by the wrist of the hand clutching the bottle fragment.

"Doctor, I urgently recommend that you – "

Something blunt stabbed his thigh, and he gasped. There was the unmistakable hiss of a drug being jet-injected intravenously right through his skin. The numbness diffused through his dilated blood vessels in a second, and his legs gave way. Still clasping the doctor's thin wrist, Spock fell to his knees and collapsed onto his side, pulling the other McCoy after him.

"F... Fascinating," he whispered, gazing wide-eyed at the empty hypospray in the doctor's free hand.

As he was losing his senses, the last thing he saw was the face – the one he knew so well – morphing into a vicious grin of a total stranger.