"So many murders committed in the name of passion and love," Sherlock sighed, having just finished a case with an ugly love triangle the day before. "Ridiculous and unimportant, but good for business I suppose."
John stopped what he was doing to look at Sherlock skeptically. "Oh come on. You've felt love before; you must have. It's not all bad. There's more than one kind of love."
"Oh, come on," John protested. "There's the love you have for family members, parents, siblings. You must have experienced that kind of love."
Sherlock grimaced. "I did not have a chance to know my mother well before she died, and my father and I never had the best relationship."
John hadn't been told that before. "Oh," he muttered. "What about Mycroft?" he asked. Sherlock frowned, and John knew he was going to need tea for this.
Sherlock thought for a moment before speaking. "Not really. I tolerate him. I would be affected if he died, but I'm not sure I can say my emotions reach the extent of love." Sherlock looked up. "Why, do you love Harry?"
"Of course," John replied, switching on the kettle. "I mean, I hate her too, and sometimes I wonder how we can possibly be related, and sometimes I want to kill her, but I really do love her."
"What about Mrs Hudson?" John asked, pulling cups out of the cupboard, double checking to make sure they were clean.
John could feel Sherlock looking at him blankly. "What about her?"
John rolled his eyes. He swore Sherlock was just being purposely difficult. "Do you love Mrs Hudson?"
Sherlock frowned. "I suppose it depends on your definition of love. I deeply care for her, that is certain. I would kill for her in a heartbeat, and I would make her tea if she asked me to. I don't know what that means though."
John smiled slightly. "Those all mean you love her Sherlock."
"Then yes," he replied, watching John pour the water.
John left the teabags to steep and stood in the doorway to the kitchen, looking at Sherlock. He was sprawled on the couch in his dressing gown and an inside out shirt, violin resting on his lap.
"Do you love me?" John asked, looking at him with tentative hope.
"No," Sherlock said, absentmindedly scratching his back with his bow.
"Oh," John said, suddenly deflated. He should have known not to get his hopes up.
Sherlock, sensing his disappointment, looked over and sighed at him. "Love is not the right word. It's so... shallow and emotional," he informed John.
"I love The Work, I love this city, I love solving mysteries and catching criminals. But... I do not love you John Watson. I need you. I breathe you in like oxygen and if you were to go I would suffocate on the dullness and stupidity that is everyone else other than you. I want to know every twist and turn of your DNA and every base pair that makes up your genetic code. I want to patent your morals and keep your brain forever if you dare to die before me. You're the most ordinary, and yet most fascinating human being I have ever met, and I want to spend the rest of my life unravelling your secrets. I hold you closer to my heart than anyone or anything else, and love simply cannot begin to describe the breadth of emotions I feel for you. So don't oversimplify or dismiss what we have by calling it love. Because it is so much more than that, so much greater, that to call it simply love is insulting." Sherlock delivered this speech in a monotone without so much as looking at John.
Once John recovered from the shock of that, he smiled and delivered Sherlock his cup of tea.