Sherlock knew there was something he could do in this situation. But he wasn't sure if he really should do it. He wasn't really of the touchy-feely sort. Except perhaps with Mrs Hudson. This was John though, out of anyone, this was the person who saw his human side. Who saw his emotions, who knew he wasn't a sociopath or any other disorder.
John was the person who saw the lonely boy inside, the one who was alienated as child and as a result, placed a wall around his heart. Out of anyone, John was the one Sherlock should and would do anything to bring back a smile to his face.
He limped over to his friend, remaining quietly behind him, still unsure of himself. Which wasn't like him at all. John had one hand on his cane, head bent, still with his back to his flatmate. The other hand was against the fridge, stabilising himself. Oh John, I've hurt you badly. Sherlock felt another tear trickle down his cheek. So he stopped thinking about it and just did what his heart told him.
He wrapped his arms around his best friends shoulders and rested his forehead against the brown hair of his doctor. He said nothing. John's head moved, Sherlock could almost feel the surprise radiate through him.
John said nothing either. Again, he was touched. His tears slowed but still fell. He rested his free hand against the one hanging from his shoulders, leaning his head back and just enjoying and allowing the comfort his normally reserved best friend was giving him. Some how this act of kindness from Sherlock made him cry more, he turned in Sherlock's arms and wept against his chest, clenching the fabric. Surprised, Sherlock simply held him, allowing his friend to vent his grief and pain instead of bottling it like the detective did.
John needed this and Sherlock would never allow anyone else to do so nor would he allow himself to be this vulnerable around anyone else but John. Neither knew how long they stayed like that, both unconsciously knowing how much they both needed it.
Sherlock had rest his chin on John's head, rubbing his back, holding him while he sobbed. It grieved Sherlock to see the normally strong, brave doctor be so fragile and grieved him more to be the cause of it. He hoped he would never have to put John in such a position again.
From the front door, a woman in deep purple watched for a moment, a smile on her face and a tear in her eye and crept back out. Lunch could wait. Her boys needed this moment alone.