The idea of a watching angel is Milady Dragon's. I have her permission to use it, and if you want to use the idea, go ask her.
I am making no money from writing this, and the only thing I own is the words. BBC Sherlock does not belong to me, if it did Johnlock would be canon.
John never really believed in the Afterlife. Not until that day in Afghanistan.
It was a tiring day. One of those days where too many soldiers have died under his care, one of those days where he questioned his decision to become an army doctor.
He was sitting on his cot, rubbing his hands over his face, thinking of the young man they'd brought in earlier. Gunshot wound just above the heart, not DOA. Wasn't a through-and-through, so there was no exit wound, but tons of shrapnel. He'd died just after John had started to work on him.
There was a hand on his shoulder. Odd, because he hadn't heard the door open. But it didn't frighten him. It felt comforting. Like it was supposed to be there.
John slowly opened his eyes and turned his head. There, sitting next to him, was a middle-aged woman, with a very long, graying red braid over her shoulder, and a pair of off-white wings coming out of her back.
She smiled comfortingly at him, her dark blue eyes sending messages of understanding and hope.
For every dead soldier many more are saved because of you.
Those men, those women did not die because of you. You did everything in your power to keep them alive.
It is not your fault.
You are doing good here.
She squeezed his shoulder, slid Her hand down his arm and grasped his hand. With a last smile, the Angel flapped Her wings once and slowly disappeared.
John went back out there with a renewed sense of hope.
His Angel was always there for him. Through the deaths, through the shooting. She smiled her largest when he met Sherlock, and an even bigger one after their first kiss. She was beside him, holding his hand, when Sherlock fell, and never left his side for three years. She kept him away from the edge of the dark pit of depression, his anchor, an ever-constant beacon of hope. The light at the end of the tunnel, because She knew something he didn't.
The last time John saw his Angel was on the bank of the Thames, lying in Sherlock's arms, quickly bleeding out from a stab wound. His Angel is standing behind him, just inside his line of vision.
"John Please. Don't go, please not now."
"I'm sorry, S-Sherlock." Blood drops from his lips, and he is coughing up more.
"I'll call Lestrade, he'll get an ambulance, but you are not leaving me now, you hear me?"
"I'd….stay if I…. could, Sherlock. But…. We're in Corringham. …You know he's…. not going to get…here in …..time." He feels himself get weaker, and the image of his Angel gets stronger, brighter.
It is time.
"I…I love you,… Sherlock."
"No, not now, no please! Please John…."
"Sh-Sherlock…."
Sherlock bows his head, tears slipping from his heterochromatic eyes.
"I don't want you to go." He says almost childishly.
Soon..
John coughs up more blood. His breathing is getting shallower.
"I love you, John. Please, don't go. Don't leave me. You made my life so, so much better. Please…"
Sherlock presses a last kiss to John's lips, his tears mixing with the doctor's.
As John died, his heart shattered, for leaving Sherlock this broken, this damaged.
And suddenly he is standing over the scene, next to his Angel.
I'm sorry, John. But it is the time. I did not want to take you away from him, but it was not my decision.
Sherlock slumps over John's body, clinging tight to his clothes and sobbing into his chest. The sight breaks John heart once more.
"Will I ever see him again?"
Depends.
"On what?"
A choice.
The first time Sherlock sees his Angel, it is just before he goes back to work. A case from Lestrade. 3 bodies, no witnesses, all the same wounds.
He is just stepping into a cab, when he catches sight of the figure on the sidewalk. People walk around him, not noticing the wings, not noticing that he is a man dead, 5 months.
As the cab goes down the street, the Angel smiles, and Sherlock sees his love again.
There will be a sequel to this I promise.