After Sherlock's death, John fell into a pit of depression. It hurt to acknowledge that Sherlock, was in deed, dead.
Gone.
Forever.
Six-foot under.
John was alone.
It hurt even more when other people acknowledged it. Reminded him of it. They might not even know that they're doing it. They could say something just a little too matter-of-factually, or disprove him-hell, you could look at him like Sherlock did and John would break down.
He couldn't handle it. How dare Sherlock leave him like that! That's when John started doing something quite unhealthy. No, it wasn't self-harm, thank god, but it still hurt him. He started calling Sherlock. Sherlock's phone was never disconnected (thanks to Mycroft, though he never said why he paid the monthly bill), so John could easily call and hear Sherlock's deep voice on the outgoing message.
"This is tedious. If I don't answer then I most likely don't want to talk to you. It's idiotic to expect a call back. Plus, I prefer to text." That's what it said. That's the only thing it said. But it was enough for John. When Lestrade found out, he tried to get John to stop; "It's not healthy, hanging onto Sherlock's ghost like this. It's not healthy John, you need to stop." John didn't care. John didn't care about anything anymore.
He missed Sherlock.
He needed Sherlock.
What was the point of life without Sherlock?
Everything was going downhill. Everything was falling apart, and John didn't give a damn. Why should he? He didn't need to care about himself, or anything else, right? The seemed to be the only thing he could think. Until the four-year anniversary of Sherlock's death, that is.
Lestrade was yelling, telling him to get over it. It was so long ago, why couldn't John learn to cope? It just went in one ear and out the other. John sat down on his chair, pulled out his phone, and began to dial. There was a small beep with every button pressed, John even pressed speaker phone so Greg could hear.. There was ringing, but it was drowned out by Lestrade. He stopped yelling, though, when it went to the machine. It was the first time Greg had heard Sherlock's voice in four-years. "This is tedious. If I don't answer then I most likely don't want to talk to you. It's idiotic to expect a call back. Plus, I prefer to-" A click, and silence. John looked at his phone in annoyance. Why the hell was it acting up now, of all times?
Then John realized that his phone was fine when he heard that deep voice once again;
"Hello, John"