"Dr. Watson is a very fortunate man," Sherlock Holmes remarked, though he did not seem terribly happy about his friend's good fortune.
Miss Mary Morstan stopped short, but did not take the bait.
"After all, he has won the affections of a charming young lady" - he dismissed his own words with a wave as he spoke - "And is now set for eternal domestic bliss. What more could a man want?" he asked as though nothing could be any less desirable.
She hesitated. "What do you want?" she asked, unsure whether she truly wanted to know the answer.
A grim smile flashed across Holmes's face, but his disinterested frown quickly returned. "I am selfish," he said at last. "You have much more to offer any man than I ever will. I freely acknowledge that I am difficult to live with and dangerous company. While you are as perfect a specimen of womanhood as one could hope for." He leaned toward her and peered at her as though she were an object of study.
She stepped backward. "My blushes, Mr. Holmes. You are too kind," she said, more to deter him than in appreciation of the compliment.
Holmes let out a sharp, barking laugh. "No, that is not what I am after. You could have any man you desire, why Dr. Watson?"
She opened her mouth to speak, but he motioned for her to remain silent.
"There is no need to answer; nothing could be more obvious. Why John indeed," he mused to himself.
Suddenly he changed track and admitted a little too lightly, "I do not have many friends." More solemn, he continued, "Dr. Watson is a rare companion. I find myself reluctant to let him go, even as I know his departure is no one's fault but my own."
"It was his choice," Miss Morstan protested.
"He does love you," Holmes admitted, with a sharp note of disdain. "You could take him, if you wished it. He would be yours if only you said the word. It is in your hands."
Holmes paused and a wide range of emotions warred across his face.
Finally, he said, defeated, "That is why I must ask you to refuse him. You will have no difficulty in finding a husband, but I will never have another Watson."
Note: I want to thank oracledivin on Tumblr for the prompt that inspired this fic! This is actually the second of two responses (the first being "Edith"). The prompt was for Kirk and Spock, but I thought the song fit Holmes and Watson a bit better, so I wrote one of each.
I'm accepting prompts at vtsuion dot tumblr dot com!