This is for urghmartinfreeman in JLC's grab bag challenge. The prompt was "You're half-human and half… dragon?" Hope I did ok! First time writing with a prompt so… yeah. Sorry if Sherlock is a little OOC.

"So…" John started. He looked at Sherlock over the top of his mug. Sherlock studiously ignored him. John sighed and put the mug on a safe-ish place on the floor, next to his chair.
"Are we going to talk about this?" Sherlock looked up from the laptop to stare at John. He was sitting in his usual chair, wearing only his pyjamas and dressing gown.
"No." He returned to doing whatever he was doing before. John continued to stare at Sherlock. Sherlock shifted in his chair.
"Are you going to keep staring at me?" John didn't answer. Sherlock sighed, closed the laptop and glared at John. "Yes?" John opened and closed his mouth, as if searching for the correct words. Sherlock was being deliberately obtuse.
"How?" Sherlock narrowed his eyes a little.
"That is hardly a proper question, John." He glared at Sherlock.
"You know what I meant, dammit." Sherlock raised an eyebrow.
"Do I? Are you sure about that John?"
"Fine." John glared at Sherlock, just to emphasise that he wasn't happy about this. "You… ah… breathed fire." John almost mumbled the last two words.
"Yes. That still isn't a question." Sherlock was obviously enjoying this.
"How did you breathe fire?" John growled on the first word, sending a small shiver down Sherlock's spine. Sherlock smirked.
"Why would you like to know?"
"My best friend just breathed fire, something that should be impossible to do by the way, and walked away unscathed." Sherlock huffed slightly.
"It was only a small amount, it wouldn't have hurt anyone."
"It came from your mouth, Sherlock." Sherlock looked at John as if he had insulted him by stating the obvious, which, knowing him, he probably had. "Was it some sort of trick?"
"No."
"Illusion?"
"They're almost the same thing, John." Sherlock seemed to get slightly bored with the conversation. "It only happens when I'm really angry."
"Why were you angry?"
"They were hurting you, John. Really hurting you. How was I supposed to not get angry?"
"Wow, you must have been really angry. You just used a double negative."
"Will you at least pay attention?" Sherlock snapped. "As you know our family is a little… antisocial, let's say." John snorted, trying to cover it up with a cough. "When my father was younger, he made a few mistakes, but he was never the superstitious sort. So when he crossed a young woman, who was known as a witch, he paid no heed to other's warnings. So a curse was put upon our family. However it didn't manifest itself until my birth." John scooted closer to the edge of his seat, eager to hear more. Sherlock chuckled silently.
"How did it manifest itself?" John prompted when Sherlock took too long in answering.
"Well… I was born half-dragon."
"Pfft. Dragons don't exist." Sherlock glared at John, making it clear that he was being serious.
"How do you explain the fire-breathing then?" John blinked, opened and closed his mouth a few times, but ultimately failed to come up with a reason.
"You're half-human and half… dragon? How does that work?"
"As you saw, when I get really angry I breathe small amounts of fire. I also have a small patch of scales which, thankfully, aren't anywhere too obvious." John puffed out his cheeks a little bit, thinking.
"Where?" Sherlock smirked and slowly shook his head.
"You don't get to see."
"Ok. You said that you were angry because they were hurting me. Why would you care so much?" Sherlock looked away, an almost imperceptible blush on his cheeks. Unfortunately John noticed.
"You're my best friend." Sherlock muttered, trying to end this particular part of the conversation.
"Yes, but you've never tried to breathe fire before."
"I didn't try. It just happens."
"Oh." John's lips twitched, trying to hide the smile that threatened to spread across his face. "So it was instinctual then?"
"I did just say that, didn't I?"
"So, when did you start caring that I was in danger?" Sherlock's eyes met John's.
"I've always cared."
"Obviously never enough to breathe fire before. We've even been in worse situations." Sherlock mumbled something, deliberately, so that John couldn't hear him. "What was that, Sherlock? I couldn't quite make that out."
"I said…" He mumbled the rest of the sentence, his eyes moving from John's.
"Still can't hear you." John taunted him.
"I said that it was the first time you were in danger since I realised how I felt." He still finished quietly, as if he could offend John with his words.
"How you felt? What do you mean?"
"I mean that I have developed… feelings for you."
"What kind of feelings?"
"More than you feel for me." He said cryptically.
"Hmph. You're wrong there." John picked up his tea and settled down to drink it again. Sherlock picked up his computer and continued doing whatever work he had earlier. After almost an hour Sherlock spoke again.
"In what way am I wrong?" John raised an eyebrow, he had been waiting for that question for a while now.
"Do you really want to know?"
"I wouldn't have asked if the answer was 'no'." John nodded. He placed his second mug of tea next to the foot of his chair, and slowly pushed his way up. He seemed to be contemplating his next move, but eventually he was standing. It only took two strides to reach Sherlock's chair, then his lips were planted firmly against Sherlock's. Sherlock's eyes widened, but he didn't flinch or move away. John gently nipped at Sherlock's bottom lip, both asking for entrance and making sure that this is what he wanted. When he opened his mouth, letting John in, he closed his eyes. He savoured the taste of John, just as John savoured the taste of him. Pulling back for air, all Sherlock could think of to say was
"Oh." John smiled.
"Yes, 'oh'."