Mycroft is my favorite character in BBC Sherlock, as well as the original novel. I've always wanted to write a story with my interpretation of the eldest Holmes brother. As it is my personal take on Holmes siblings and their dynamics, it contains some (or a lot) of OOC-ness. Please bear this in mind as you read the story!
The story is also cross-posted at AO3.
"Were you really going to let him die?"
Sherlock asked. He and Eurus had just finished another one of their symphony. His sister stared at him unblinkingly from across the glass wall.
"Yes."
"Why? Why do you hate him?"
"Why not?"
"Well, enlighten me," Sherlock scowled.
Eurus smiled.
"You've always been my favorite, Sherlock."
"Enough about me, tell me why you hate Mycroft enough to make me kill him."
"He was never as interesting as you. Nothing seemed to make him spark… he was too soft, sentimental, reserved…." Eurus went on, dreamlike.
"Wait, wait. Soft? Sentimental? Not sure we're talking about the same brother here, sister dear," Sherlock scoffed.
Eurus observed at Sherlock's face, as if searching for something. Then she smiled again.
"Of course. How frail, our brains are. You didn't just forget about me, you forgot about Mycroft too, haven't you?"
"I didn't forget, I rewrote the memories. And it was only about you and Redbeard, I remember everything else. Crystal clear," Sherlock scowled.
Eurus just kept on smiling, her eyes twinkling in sudden merriment.
"Sleep, my love, and peace attend thee—" Eurus started to sing in a soft alto.
The simple melody of a lullaby washed over Sherlock.
It brought up so many emotions and memories that they were all tangled together, nothing tangible and all mixed up into a confusing stretch of darkness. Then Sherlock suddenly opened his eyes in a small room in his mind palace. A place he didn't even know existed.
Young Mycroft stood in the middle of the room, his arms carrying Sherlock sniffling against his chest.
"—All through the night, guardian angels and God will send thee, all through the night—"
Mycroft softly hummed the lullaby as he drew slow circles on the small boy's back.
Suddenly, the door opened and a young girl—Eurus—came in.
"Eurus, please. You must stop hurting him," Mycroft pleaded.
"But he liked it. We had fun together," Eurus said, her voice strangely void of emotion just like how it was now.
"If he's in pain, that's not fun. It's not fun at all. Please, sister dear."
Sherlock, who was half falling asleep at that point, stirred and saw Eurus.
"Go 'way!" Fresh tears came down his already tear-streaked face.
"Please Eurus, leave. I'll find you in a bit, okay?"
Eurus observed them in silence. Then she turned around and left, door closing in a loud bang behind her.
"Shh, it's alright, brother mine," Mycroft whispered and resumed his singing.
Well, that was short. It was a prelude of sort to the rest of the one-shots, which I'll begin posting soon.
By the way, does anyone recognize the lullaby? :)