Mrs Hudson phoned John out of concern for him and his family but the doctor insisted that he was fine and hadn't a clue as to why Sherlock did what he did beyond the detective having received a call from his brother and having to leave suddenly. John then phoned Mycroft who gave a vague explanation of what had happened, leaving out the true reason. He informed him that he'd said something to make his brother upset and left it at that. John expressed his concern to him and volunteered to check in on Sherlock but Mycroft declined the offer, insisting that he stay home with his family while he handled it. This was something he had to do alone as he was, after all, the cause.
Mycroft pulled down his sleeves, straightened his tie and cleared his throat before walking into the building. Mrs Hudson stood at the foot of the stairs, looking up, and turned only when she heard the door close.
"Oh, dear," she said. "He's upstairs. I don't know what's happened."
"Not to worry, Mrs Hudson," he consoled her, kissing her on the head with uncharacteristic tenderness towards the landlady. "I can assure you that everything will be fine."
"I do hope so. I've never seen him like this."
He pressed his lips together and looked up as she had. "Have some tea, Mrs Hudson," he said as he made his way up the stairs. "I'll handle it."
Mrs Hudson nodded and went to do as he had said.
He didn't knock but the sound of glass being pushed by the door announced his presence to the flat's sole occupant, who heard it from his bedroom and pressed a pillow against his ears to block it out. Mycroft didn't call out and didn't even go looking for his brother. Instead he cleaned up the shattered lab equipment and sat down in John's former armchair.
It was three hours before Sherlock came out to see his brother, dressed in pyjamas with a blanket wrapped around him. Mycroft was just sitting there silently with a book in his hands.
"Treasure Island?" Sherlock asked, taking a seat in his own armchair.
His brother nodded in the affirmative and set the book aside. "Your favourite."
"I remember when you bought it for me."
"After you threatened me with your wooden sword. Then when that didn't work you told me you'd suffocate me in my sleep with your scarf.
The two laughed at that for a few moments but quickly fell silent again. Sherlock's eyes stayed locked on the book as his vision blurred. "There must be some way to..."
"I'm afraid that it cannot be solved, brother mine. Not even by us."
Sherlock closed his eyes as tears began to overflow from them. "I can't..."
Mycroft could take it no longer and in an outburst of strong, brotherly compassion he stepped over to his baby brother and pulled him into his arms. Sherlock gripped his vest and began to sob silently as Mycroft rubbed his back gently. They stayed like that until after the sun went down and Sherlock's tears had dried.
"I can't lose you too," Sherlock whispered as Mycroft pulled away. "I still miss Sherrinford."
"I know," Mycroft replied softly. "I do too."
"Don't go. Just please... don't go."
"I'm right here, William."
Sherlock calmed down a little more at the sound of his real name and let go of Mycroft's vest. "I'm tired," he whispered, holding his blanket tighter.
"I'll read to you until you fall asleep."
Mycroft turned on the lights and sat back down in his chair, picking up Treasure Island again. He gave Sherlock a reassuring smile and started to read until his little brother drifted off. "Squire Trelawney, Dr Livesey, and the rest of the gentleman having asked me to write down the whole particulars about Treasure Island..."
Eventually, months later, he knew he had to finally tell the others, beginning with 'Anthea' (as John called her, though Mycroft knew her real name). She had promised to organise a good funeral for him and even shed a couple of unexpected tears. Mycroft had held her for a minute before they continued in their usual manner.
Then he decided to tell the others all at once, except for his parents. Greg and Molly sat in silent shock. John and Mary showed more concern, though much of that concern was also for Sherlock, who they knew would be struggling more than he showed. Mrs Hudson had cried and even hugged both Holmes boys before going to make tea (which they knew was to distract herself). Mycroft wondered how the woman would have reacted if it had been Sherlock instead of him.
When he went to see their parents, Sherlock had decided to go with him (partly to offer support for his brother, but mostly out of fear that his brother would pass away without him being there, and so he was determined to stay by his side). Mummy Holmes had cried, holding her eldest son in a warm, firm embrace until long after the tears had stopped. Their father shed a few tears but was determined to show strength in this dark time, offering a shoulder for Sherlock to lean on, which the youngest Holmes son accepted passively as though he were a young boy again.
Sherlock took on the unlikely role of housekeeper during their stay, providing warm tea and biscuits, tissues and even cleaning from time to time. He was, however, always casting glances at his brother, who seemed weaker yet more relaxed than he'd seen him in years, even laughing as their father told terrible jokes and their mother showed him photos of young Sherlock and Sherrinford.
It was on the fifth night at the Holmes house that Mycroft announced that he would go to bed early, without giving a reason, kissing Mummy on the cheek as she hugged him goodnight. Mr Holmes gave Mycroft a small pat on the shoulder before Sherlock pulled him into a sudden hug.
Sherlock could hear the true meaning of his words in his tone and hugged him tighter, one stray tear falling down his cheek.
Mycroft cast one more glance over his family, the three of them looking at him with sad understanding in their eyes, before he turned and walked to his bedroom.
Mycroft laid down on his bed that night, looking around the room that had barely changed since he'd moved out. The soft moonlight that shone through the window illuminated everything with a hauntingly beautiful glow; from the knight figurines on his shelves, to his various books on science and history, to the photo of him, his brothers and Redbeard that hung on the wall opposite his bed.
He could hear his brothers footsteps just outside his door, shuffling on the spot before he moved on to his own room. The sound of Sherlock's violin drifted to him in the still and solemn night, Mycroft's favourite piece being played to him as a final lullaby. His eyes drifted shut to the music, a long overdue and peaceful smile on his face as he fell asleep...
And just like that, in the middle of the night, Mycroft Holmes was gone.