What bothered Loki was not that Thor was lying when he said he loved him. After all, who could lie to him, a master –THE master – of lies and tricks? No, Thor believed he loved him, as their mother and even the Allfather did when they spoke the words to him as if he was truly their son.
What bothered him, what kept him awake of a night, what cut into him like sharp diamonds into his skin whenever Thor's bright eyes turned to him, was that however many times he said it, however much he thought he loved him, he had hardly once in centuries acted like it. He did not treat him like even an equal, like someone worthy even of respect, let alone love…
Love, he thought to himself time and time again, so angry sometimes he could spit bitter venom. Thor does not know what love means!
And if he even ONCE more told him to know his place, or watch his words, or show some damned respect then by all the gods he was going to push his favourite dagger, the one Thor had given him, of course, of course, right into his stupid chest and twist it – not kill him, never kill him, just hurt him and maybe kiss his mouth and paint him in blood and all the while tell him how he loves him, loves him…
Which would be no lie either, but he thinks so long and so hard on hurting Thor that he found himself wondering if perhaps he did not know what the word means either…
We are a perfect pair, then, he thought with a sour laugh, and when Thor came to him late at night, not really inebriated but fuzzy and louder than ever and honest from the ale he had been sharing with his friends, confessing with careful but charming words that surprised Loki by reaching into him, weakening him, a taste of my own medicine, to wanting things that set him aflame inside just to think about…
Oh, oh, how he wanted to give in! But should he, when giving Thor his own twisted love would be tantamount to forgiving him for his own? Or should he reject him, scorn him? Here was his chance to hurt his brother, more than he had hoped for or imagined when physical pain was of so little consequence to Thor… Here was a chance he might never have again and he could only stand, watch Thor's confession that came as much from his nervously active hands as his soft mouth, frozen in indecision.
"…because I love you so much," Thor finished his surprisingly touching speech as Loki was still caught between his twin desires, so intertwined as to surely be inseparable in him forever, to hurt Thor and to have him.
"Prove it," he hissed back at his brother, because perhaps he could feed both his desires at once.
"Prove it?" Thor echoed, looking stunned. "Loki, surely… Perhaps it is new to you to know that my love for you is…is what it is," he said, stuttering and blushing an attractive pink for the first time in this baring of his soul. "But you must know that I love you? I know that I tell you often."
He looked so confused, bless his handsome face, curse his naïve, self-absorbed heart, and Loki was struck by the irrelevant stray thought that he would never use his dagger on Thor after all – it would be like stabbing a particularly adoring but troublesome pet dog.
Still… He deserved some pain.
"I do not believe you love me," he said, enjoying the stricken look in Thor's eyes even as he felt the same pain to which he was subjecting his brother; an ache in his chest, the sting of tears blossoming in his own eyes just as Thor's shone more than ever in the magic light that kept his room in a soft glow at night. "I think you are lying," he lied.
"Lying! No Loki!" Thor cried, distraught, apparently too shocked even for the anger that normally came so easily. "I do not lie, especially to you, and nothing is more true than my love for you!"
Loki longed to rush forward to him, to embrace him, to be doing unspeakable things to him right now, but instead made himself stay as still as stone, cold and disbelieving on the outside – a challenge, a question of mind over matter that stretched even him when on the inside his heart was warming, hesitantly, even fearfully starting to forgive the centuries of neglect; when his body wanted to shake with anticipation of how they might spend the night together if he could only sting Thor the right amount, hurt him enough that they both got what they wanted; and when deep down, so deep that he wilfully refused to acknowledge it, he was aching with relief because even if it was twisted, even if it was wrong, he did know love – perhaps they both did.
"Prove it!" he ordered Thor again, allowing some of the heat that threatened to consume him to enter his voice this time. "I want you to prove it to me."
And Thor did.