Thor almost hadn't recognised his brother at first.
It had been three centuries since they'd been separated. Three centuries since the frost giants had emerged from a snowstorm to overwhelm the palace and dragged Loki away with them. Three long centuries of war and treaties and yet further war, and none of it ever enough to persuade Laufey to give "his" son back.
In all that time, Loki had been smuggled from one secret location to another, hidden even from Heimdall's sight by the ancient magic of the other spoils of their raid. Many on Asgard had whispered that he was already dead, bled out on an altar to ensure Jotunheim's conquest of the Nine Realms.
But here he was, alive. As Thor had always known he had to be.
He was older, and he looked almost like one of them now – blue-skinned and crimson-eyed, clad in nothing but a kilt and jewellery, his jaw and skull shaven bare in a way that made him look sickeningly like a thrall – but Thor didn't care. He'd know his little brother anywhere.
He'd been so overcome to recognise his brother now, not a captive but a warrior, not a boy but a haughty young man, that he hadn't flinched at the rage on his strange new face, nor made any move to stop himself being shoved against a tree.
After all, Loki had every right to be angry with Thor for taking so long to find him, and for failing him so many times; if Loki wanted to hit him, Thor would welcome it. It would be a relief to have something as tangible as pain to prove that he was not dreaming, and it was no more than he deserved.
It took Thor a moment to process the dagger that Loki was holding to his throat.
"Thor of Asgard," Loki hissed in the giants' tongue, "You are to stand trial before his majesty King Laufey for your crimes against the Jotun people."
Thor almost laughed.
There was no jest in Loki's tone, nor in the gleaming eyes of the dozen giants emerging from the gloom behind him.
Thor tried to push Loki off – always a simple task before – but Loki struck an easy blow to his gut, winding him and slamming his spine against the tree trunk. Before he could recover, snow snaked up from the ground and formed shackles of ice around his wrists and feet. There was a touch of green to it – their mother's magic, mingled with the monsters' – and Thor knew even before he tried that he would not be able to break these bonds.
Thor squared his shoulders and stared steadily back at his brother. "You call me a criminal," he said in pure, uncompromising Asgardian, refusing even to layer the All-Tongue over it, "when Laufey still schemes to see every race in the Nine Realms in chains but his own?"
"Our own," Loki corrected in Jotun, without a flicker of shame.
It was a worse blow than any Loki had ever landed on Thor with his fists.
For a heartbeat, dread and betrayal rose rapidly in Thor's mind, like the ground rushing upwards before unconsciousness hit – but he pushed them doggedly back down.
It was only as Mother had warned him. Loki had been gone for so long – there was no knowing what these creatures might have done to him, nor what Loki might have had to do to survive.
He could not let Laufey cloud his mind with such craven, twisted lies. He knew perfectly well who his enemy was, and it was not his brother.
He knew the difference between a kinsman and a captive, too. He knew that a true father would not keep his son trapped, concealed, and alone, nor value him only as a weapon or a tool. A true father would not lie or hurt his son without cause, nor raise him in the fear that failure would mean his death.
So Thor knew, despite all appearances, that Loki was no more free in this dark, desolate realm than he was himself.
And Thor had vowed before their father and all the people of Asgard that he would bring him safely home.