In most universes, Loki discovered later, it was Doom who started it. Perhaps the instinctive recognition of this was why he so rarely betrayed Doom.

Oh, a little double crossing here or there, one or two incidents of leaving him to take the blame, occasionally allowing him to be almost killed when their joint plans fell through – this was all part of the game, like the poison with which Doom had laced Loki's food the first time they had dinner together. For how could either of them respect the other if they didn't sometimes prove difficult and unexpected and perilous to know?

But serious betrayal – irrecoverable harm? He had not done that to Victor. Nor had Victor done it to him, yet. Their truce held at a level of what he had begun to think of as 'friendship'. So when he had needled Doom into inviting him to see the abomination he was working on today, Loki only had four or five second thoughts before following the mortal madman down into the sacrosanct dankness of the furthest of his laboratories.

Outside the door, they paused to tap in pass codes, for the gem in the lock to recognise Doom's magical signature. An intriguing thing, this marriage of science and witchery. Not one Loki cared for – why tame the life force of the universe into bottles, when it might rage wild and limitless across one's skin? But still a thing to watch in the hands of others. He sniffed and smelled amniotic fluid, old blood beneath fresh disinfectant, the throat-closing scent of burned bone, and something far more...

His chin went up. He snuffed again, frowning. Ice, and the faint ketone smell of frost giant, and... himself?

"Ah." Doom noticed his sudden shift into attentiveness. The welded mask inclined, and that was all the expression of which it was capable, but his voice flexed in smiling challenge. "I thought this would interest you."

Lights flickered on one by one, dimly at first so that the forms within appeared to create themselves out of shadow. Along Loki's back and across his shoulders the skin stirred, standing on end like the ruff of a wolf. His eyes widened and his jaw dropped – the room was full of him, although it was him in Jotun form. Tanks lined the wall and copies of him floated there, motionless, neither dead nor alive. Some were infants, some grown to adulthood. On the examination table one of the adults lay cut in half, a saw poised above the trailing end of his spine. Hence the smell of burning bone.

There was a brief, quiet moment where Loki did not know what to think. He leaned forward and poked with fierce curiosity at the internal organs on view. He was aware, all around him, of a vast, quiescent potential. Magic, woven into his DNA, waiting, brainless and at peace.

Then he found himself smiling, flattered beyond words. "Oh Victor! How very much I must fascinate you. I declare I am quite touched."

"Hm," said Doom, and offered Loki a journal in which he had recorded his observations in careful copperplate handwriting. "Only you could take an exploration of your weaknesses in the light of an attempt at courtship."

Courtship? Loki thought, not wholly averse to the idea. Say it with vivisected clones? Oh, he did like Victor – the man could be counted on to do things that no one else had done, things that no one else had thought. And in a lifetime of watching everything repeat, over and over again, the spontaneously weird was extremely welcome.

"If that's your intent, you will be sadly disappointed," he waved a dismissive hand, dropped the journal casually into a pool of...bile, by the smell of it... and went to lean against the largest tank. A small inquiring tendril of power and the thing inside opened red eyes and looked at him. He still couldn't tell if there was a mind there or not.

"Because you are invulnerable?" Doom scoffed. "Normally your lies are are more polished than that."

Loki turned to look at him, leaning his palms back against the reinforced glass, weakening it. He was not immune to sentiment – didn't like to see any part of himself in a cage, even these inferior copies. If it had the wit to attempt an escape, it now had the means. If not, it was not worth saving.

Doom had missed the point, as usual. "Because these are Jotnar, and I am not. Studying them will give you no reliable information about me."

Brushing off the journal, Doom inserted two long wires into the back of the dead clone's skull, fired up the computer to which they were connected. Covered in armour from crown to sole, his body language was muted and his face unreadable. Loki was certain that he heard disappointment, nevertheless.

"They share 100% of your DNA. They are Jotnar, just as you are Jotun. I did not think you lied even to yourself."

Loki's armour was far more adaptable. He chose a self-depreciating smile as he ruled a firm line beneath the hint and offered no more. "Then clearly you do not know me as much as you wish."

Because although Doom's fascination was flattering – although it was delightful, and unexpected, and glorious, to have anyone try so very hard to understand him – it would be terrifying if he ever actually succeeded.

Distracting himself from that thought, Loki parted the clone's black hair to look more closely at the base of his horns. They were covered in a downy material, like the new antlers of deer in the spring. Rubbing it off revealed enamelled bone, whiter and smoother than teeth. With a vicious moment of disgust, he thought so that's why the helmet. Because the monster in me yearned for its true shape.

Perhaps there were things he could learn from these perfect offspring. But they wouldn't help Doom, who held only one half of the puzzle. For Loki wasn't Jotun. Shapeshifting was not a matter of changing only the outward appearance – if he changed into a horse he took on all the physical characteristics of a horse. If he changed to an Asgardian, he became an Asgardian...

In a tank that looked more suitable for tropical fish, there floated a copy of himself at about four weeks old. Loki had seen this one out of the corner of his eye when he came in and refused to look again. It reminded him he was not much of an Asgardian either. He was what happened when an untrained infant, scarcely born, weakened by starvation and neglect, instinctively adopted a form of which it had no knowledge or understanding. He was riddled with mistakes and ambivalences, some odd, imperfect thing half way between one species and the other. And unique – the only one of his kind in the universe.

Had he chosen an Asgardian form once he had the knowledge and the training to do it right, he would not have elected to retain so strong a family resemblance to Laufey. He wondered at times whether Odin's coldness, his cruelty over the years, had been prompted by the fact that when he looked at his younger son - innocent and anxious and eager to please - he saw the face of his oldest enemy looking back.

Doom bent over his computer, coaxing it to full life. A series of graphs and schematics displayed on the old fashioned screen, and the man himself seemed absorbed enough to overlook the way Loki's fingers were trembling. They cramped so, the fingers of his right hand, when he thought of the man who was not his father, as though they were still trying not to let go.

Loki clasped both hands behind his back to still this tell, and thought about hunger instead. His infant self must have got the Asgardian digestive system wrong. How else could he have out-eaten Volstagg daily and still be wracked with what felt, and looked like, endless famine? Why else would he have felt, when the casket shifted him fully to Jotun form, as though his belly was full of cold writhing eels?

Well, all right, perhaps that last thing had been mere horror. The principle remained: Whatever Doom was looking for, he wouldn't find it in this pure Jotun form. Since the day Odin picked him up, nothing about Loki would ever be pure again.

And now even these copies of himself were making him feel that he wasn't good enough.

No, it was they – stupid creatures – who should be ashamed of themselves, floating passively here, waiting to be carved up. Why had they not broken free? This one on the table, with his ugly black fingernails and his fuzz-covered horns, why had he allowed this to be done to him? Why had he not crushed Doom's head, or buried the new sharp points of his tines in the man's stomach, when Doom bent over to his work, and ripped?

He laughed, once, nervously. Stifled giggles behind his hand, suddenly aware that this place of torture was beginning to distress him. Too many memories, forgotten too incompletely. "Do they never try to escape?"

Doom straightened up. What was visible of his eyes suggested he was smiling. "They do. But they have all the knowledge and coordination of newborns, and are easily contained."

Now Loki was no longer amused at all. Another emotion was trying to replace it. He could feel it, outside the doors of his mind, inchoate, pressing, not yet identifiable. "Another way in which they are not like me."

"Yet they serve me well enough," Doom indicated the computer monitor with a smug gesture. "Look here. If I feed enough data through their brains, I find I can predict your actions in any situation to an 83% level of accuracy. I'm sure with some refinement I will be able to get that up into the nineties before the year is out."

Ah, it was fury. And now he was shaking with it, and the glass was cracking, splintering into shards that sucked out into a whirlwind of bright edges all around him. They smacked across Doom's armour and shattered into smaller and smaller pieces until the very air was clawed with diamond dust. The clones had time only to open their eyes and scream before they were abraded into a storm of gore.

Nodding to himself, Doom covered his eyes with his armoured hand and backed through the door. He sealed it behind him as his computer tore itself into component parts and the electricity within kindled into welcome, cleansing flame.

As Loki stood in the centre of his own maelstrom of razors, blood and flame, helpless to stop his own reaction to the repugnance, the obscenity of this, he tried to tell himself he had not seen the final line of figures on the now melted screen.

Probability that Loki will destroy the lab and all evidence – 91%

How could Doom know that much, when Loki himself didn't know if he was offended or outraged, betrayed or terrified or destroyed?