The nearly-manic smile that had been splitting Loki's face slipped, and he took an instinctive step back from the man who stood before him. He had been so sure. Was it possible that this wasn't...? But no. No, he had seen Thor in much stranger situations, wearing guises that Frigg herself would have walked past in the hall. This man he faced was little more than a beardless boy, but there was no mistaking him. It would be simple work- the addition of a few stone muscle, a beard to cover that absurd jaw line- to return him to his old appearance. This was Thor, he knew this was Thor, and any suggestion otherwise was sheer folly.
Or, his doubts whispered, he could be mistaken still. Images were fickle, no one knew this better than him. This could be no more than a ploy, something to do with the events of the night. It could be an accident, one of life's strange happenstances that he had run into one of Thor's descendants. Or, perhaps, the long years had finally driven him mad.
Those doubts were all that kept him from taking the boy by the shoulders and shaking some sense into him. Instead, he stood his ground and spoke, in a more subdued tone this time (and, he noted with some chagrin, in the correct language.) "You are Vingthor, are you not? Son of Odin and Frigg. Protector of Midgard. They called you Sonnung and Rym, Hlorridi and Einridi, though we both knew that last was never true. I liked the other names best: Oku-Thor of the cart, Ennilang of the wide forehead. You carried a hammer called Mjolnir. A hammer I procured for you," he added with a trace of annoyance, "and which you seem to have lost."
He scanned the other man's face for some sign of recognition, stepped forward, and raised his chin in defiance, feeling his own fists clench by his sides. The challenge was the best he had, the only one he felt sure would work. "Stand forth, Thor, and answer to your name, or you are no man."