A/N: In my head cannon, John is equal parts kind caretaker and BAMF, so it stands to reason that he would be a prime candidate for guardian angel duty! This story has been bouncing around in my noggin' since viewing episode one, so I'm finally giving it life. Also, you should be aware of the fact that I'm pretty busy, so whether or not I continue this story is completely up to reader feedback. Aaaaand that is all. Enjoy!

Disclaimer: The Sherlock Holmes books and all of their various incarnates are not mine, and I am in no way attempting to claim them as such. This story is a work of fanfiction not intended for any sort of copyright infringement.

When John Watson was first assigned to Sherlock Holmes, he assumed that there was some sort of mistake.

He was fresh from his "deployment" as a guardian for Victor Trevor, a soldier shot through the heart in Afghanistan. That was the thing about being a guardian angel—you might do everything right, and it still wouldn't be enough if it was a person's time to die. John had liked Victor. He was young, affable, and incredibly brave. John had subtly helped the young soldier through the various hazards of his two year deployment, only to have his assignment end when Victor saved almost two dozen men from friendly fire by sacrificing his own life.

John watched miserably as the young man was pronounced dead, and followed him back to London like a silent sentinel. He skipped the funeral, where he knew that the twenty-two year old's single mother would be, because he didn't think he could handle her grief.

For the past two hundred years, John had specialized in guarding soldiers. As both a doctor and a ex-military man himself, he had a unique ability to be a ferocious protector while still remaining emotionally detached enough to do his job for years on end. So when his gate keeper informed him upon his return that his next assignment was a young genius drug addict, he was surprised and a little shaken.

"Did I do something wrong?" He asked, sure that this was some sort of cosmic punishment. He was a soldier and a doctor, not some sort of social worker. He was ill-equipped to babysit a self-destructive, over-grown child.

John's expression became one of intense remorse as he thought of his previous charge. "Was it Victor? Could I have saved him?" He demanded.

The gatekeeper only smiled kindly.

"Perhaps," he said cryptically. "But then, the men he died protecting would surely have perished. You did everything you should have, and it is not our place to rob mankind of their ability to choose their own fate." There was a significant pause as the gatekeeper across from John chose his next words.

"No, John, you did not fail. You have been called in because I think you can succeed where no one else has. Your charge, Sherlock Holmes, is a key player in upcoming events that will touch millions of lives. As things stand now, however, he is at the edge of a very steep precipice. He needs someone to guide him in the right direction. I am sure that you would do well in this position"

John knew he should be flattered, but it did nothing to abate his trepidation.

"Why me?" He asked. "Why not send one of the others? I'm not really a patient person, and it's not like I'm smart enough to operate on his level. I'm probably the worst guardian you could have chosen."

"On the contrary, I think you are exactly the person I'm looking for," the heavenly being replied- kindly, but with a note of finality. John wanted to argue, but he knew that it would be futile at this point. For better or for worse, he was officially Sherlock Holmes's divine caretaker. The doctor nodded his assent, and stood up to leave. As his hand touched the doorknob, the gatekeeper spoke up one final time.

"Oh, and John? I've reviewed your file, and I think you've served long enough. This is your last assignment before you move on, so make sure you have no regrets."

The doctor's eyes widened in surprise and he considered the implications of that statement. Still, John knew that he wasn't expected to reply, so he merely nodded to show that he'd heard and continued his journey out into the blinding London sunlight.