Could you do something like the villain finding out his nemesis hero is member of his nearly extinct (fantasy?) species?
Like the villain thought he was the last of his kin?
"You..." The villain's eyes widened. "You're..."
Between wearing either heavy make-up and coloured contacts in his civilian guise, or his hero mask when he wasn't, the hero could usually pass as human.
Unfortunately, his mask rested utterly useless in the villain's hands and he hadn't had time to do a full face before rushing out the door. The inhumanity of him was thus blatantly visible beneath the villain's devouring gaze.
"A monster?" the hero snapped. "That's rich coming from you, you-"
The villain reached up and, with the careful press of a button, his own mask slid away.
The whole world, and all that he was fighting for dropped away as his heart leapt and his mouth went dry and it felt like every atom in his body hummed with recognition.
The villain's eyes were the same purple shade as his own - a dark orchid-esque colour that humans couldn't quite filter properly and had no entirely accurate name for. The line of his cheek had the same glimmer of scales, though the villain's were a shimmering pearl compared to the hero's blue. He hadn't filed his teeth down to blend in like the hero had either. They were carnivore-sharp.
Dragon. In his more humanoid form, certainly, but a dragon nonetheless.
Several key facts slid into place.
"Oh," the hero said, breathless. The old language suddenly felt ready and perched on his tongue like a waterfall. He swallowed it down.
"I thought I was the only one left."
The hero's brain churned, as he struggled to compute the astounding evidence in front of him. Because he couldn't - the villain couldn't - except he obviously was.
Had he been stealing for his hoard?
"I thought I was alone," the villain said. "Are there others?!"
Mutely, dumbstruck, the hero shook his head.
He'd thought he was alone too. For so long, so very very long, he'd thought he was the only one left. And now - now. The hero scrambled belatedly to his feet, with a groan of pain. He could feel panic rising. Panic and hope and fury and longing.
The villain closed the gap in an instant, as if scared the hero might run. He curled one hand around the front of the hero's suit to hold him in place, pinning him back against the wall with a matching strength that suddenly made so much more sense. The wall behind them gave an ominous shudder.
His stare raked over the hero's body, like he could slip beneath his clothes and perform a full catalogue or history, before snapping back to the hero's mouth. His teeth.
"What did they do to you?"
"They didn't do anything. I -" There were too many questions, it was too big. The hero had no idea where to start. He reached out to grab his mask back from the villain.
The villain hurled it aside, well out of the way. His freshly-freed hand gripped the hero's wrist. Tight. Possessive.
"Why are you protecting humans?" the villain sounded somewhere between bewildered and livid. "What's wrong with you?"
The hero bristled, the fury clearing his head a little bit too. "What's wrong with me? What's wrong with you? You nearly torched half of London, are you insane?"
"They hunted us. I thought I was the only one left. Are you -"
The villain swore in old tongue. Fire-tongue, though the hero had guessed that much.
He could practically feel the heat rising off the villain, sudden and foreboding. His instincts swerved this way and that; torn between the violence of enmity, of every vicious memory they shared, and all the sheer longings of a home he'd thought lost forever.
Before he'd even fully realised it, he'd reached out, palm searching the villain's chest in turn, finding his heartbeat. Slow. Much slower than a human's could ever be.
"Oh, god," the hero said.
"You even sound like them," the villain said, tone not quite kind enough to be wonder. "I really thought you were human. What did they do to you?"
"They didn't do anything! Just - shut up. For one second, just shut up. I need to think. Because you - you're - oh god."
There were many arguments the hero could have made, never mind that the whole point of a secret identity was to fit in, but all he could focus on was the enormity of it.
He didn't have to be alone.
The villain's hands moved up to his face, clutching his jaw, cradling him. The purple of his eyes began to deepen to flame.
"Come with me," he said, fully switching to the old tongue. "We shouldn't be fighting each other. You're young - you must be young if you're on their side - we'll talk. You'll tell me everything."
The worst person the hero knew was the only one who could possibly begin to understand.
The hero ripped himself free, and bolted.
