He would do anything to get back the one he had lost.
Anything.
He had drifted through all the so-called 'stages of grieving'.
At first, denial, being sure that his eyes had betrayed him, that the body lying crumpled on the sidewalk wasn't the man he had grown to love.
Being absolutely certain that the body in the closed casket wasn't that man, that the body buried in the graveyard, with the headstone baring his name, wasn't really him. It couldn't be. He was immortal. Beautifully so. He had often seemed barely human while he was alive, so why couldn't it be the same while he was dead?
Next was anger.
The first things to be smashed were all of Sherlock's glass vials and experiments in the kitchen, carefully preserved for if -when- he came back. After throwing them all at the wall in a fit of fury, he sank to the floor, sobbing.
After that, almost everything else in the flat had been thrown or punched at least once. Similarly, he had collapsed onto almost every flat surface, tears streaming uncontrollably down his face.
The third stage was bargaining.
He didn't really go through that, or if he did, it was mixed in with the anger and then the depression. With Sherlock's death, he had very nearly stopped believing in any higher power, so there was really no one to blame. Aside from himself, of course. And he never stopped blaming himself, never stopped thinking that it was his fault.
Then, the depression came full-force.
It was all he could do to even get up in the mornings. He knew that he had to leave the house, go to work, buy food, but all the time he was doing that, he was swimming in grey.
He stopped doing much for himself, stopped trying to keep in touch with friends, stopped trying to do anything but the bare minimum.
He would sit and stare at the blank television screen for hours, listening to silence, seeing nothing but memories of blood soaking black curls and running across high cheekbones.
It seemed like there was nothing but lethargy and despair left, no reason to wake up in the mornings, no reason to eat or work or take a shower. He tried to start feeling again, but nothing worked.
When he slashed open his arms, putting dozens of horizontal slices onto his arms from wrist to elbow, he didn't feel anything but fleeting pain. The red blood, falling in heavy droplets, brightened up the grey, but only for a short amount of time. Not nearly long enough.
He could feel his body weakening, with every meal he couldn't bring himself to eat, and every day that he couldn't pull himself out of bed. His ribs were slowly becoming more and more visible, while he couldn't bring himself to care.
There was no point in caring about anything, not when Sherlock had been dead for almost two years. Not when he had been alone for the same amount of time.
So when he decided to step off the roof of St. Bart's on the second anniversary of Sherlock doing the same, John could only feel relief when his body hit the ground and he slipped into darkness forever.