A/N: I wrote this after watching an episode of Dawson's peak. When he is explains what a soul mate is and the speech that John makes is from that episode. That part from the episode reminded me of Sherlock and John.
Disclaimer: I do not own Sherlock or the Dawson peak references.
Soul mate
John was sat in his chair looking though the newspaper. Sherlock was in the Kitchen looking through his microscope. All of a sudden John's six-year-old niece came into the room and jumped into John's lap. John laughed and smiled. John saw Sherlock glance as the six-year-old made her self more comfortable. John put down his newspaper and turned his attention to his niece. "What have you've been up to?" John asked.
"I've helped Mrs Hudson make a cake." The six-year-old replied. That's why she had cake mix all over her mouth. "Can I ask you a question uncle John?" She asked.
"Of course you can." John answered.
"What's a soul mate?" She asked.
John looked away for a moment and then he saw Sherlock and he had his answer. "A soul mate it's like a best friend but more, it's the one person in the world that knows you better than anyone else, that someone makes you a better person. Actually, they don't make you a better person you do that yourself because they inspire you. A soul mate is someone who you carry with you forever, it's the one person who knew you and accepted you and believed in you when no else did or when no else would and no matter what happens, you will always love them. Nothing can ever change that." John explained to the six-year-old.
She looked up at him and hugged him. John looked at Sherlock and realized that his soul mate had been there all along.