I got the idea for this from "Frozen" when Anna sings "Do You Want to Build a snowman". Yes, the lyrics are changed. That started out as a crackfic that somehow turned serious. Sorry not sorry.

Small Sherlock: Mycroft! *knocks on door*

Do you want to play deductions? Come on let's go and play!

I hardly see you anymore, come on out the door!

It's like you've gone away!

We used to be best brothers and now we're not,

I wish you'd tell me why.

Do you want to play deductions? Doesn't have to be deductions!

Young Mycroft: Go away, Sherlock.

Small Sherlock: okay bye.

Time Passes...

Young Sherlock: *knocks*

Do you want to play deductions?

Or experiment on frogs? I think our experiments are overdue

I've started talking to the skull that's in the hall!

It gets a little lonely, all these empty rooms

just watching the hours tick by...

Years Later, The Reichenbach Case

Sherlock entered Mycroft's home. The office door was shut. If Sherlock wanted to, he could be stubborn and claim he didn't need his brother's help. His homeless network and Molly Hooper could do it very well by themselves. But deep down, Sherlock knew he needed Mycroft's help. Or at least his approval. Maybe their relationship wasn't the best. Maybe they were really just hiding behind their deductions and schemes and the need to constantly one-up the other, ignoring the reason why they needed each other. Because no one else understood them better than each other. No one else in the world understood Sherlock's brain better than Mycroft, and vice-versa.

He approached the office door, knocking quietly.

"Mycroft, I know you're in there," his voice was low, trying to disguise the emotion that seemed to choke his words. Molly stood some distance from him. She nodded encouragingly when he looked back at her. The pacing behind the door stopped. "People are asking for a statement, Molly is telling me to have courage and I am trying. I am waiting here for you. Just...let me in," he paused, taking a breath. "We only have each other, you know. No one else in the world understands me, my mind, as you do. Except for one man, and he must be stopped. So, what are we going to do?"

There was no noise on the other side of the door, the light was switched off. Sherlock looked back at Molly. The rejection of his brother seemed to bring him back around to the days if his childhood, knocking on Mycroft's door, begging him to come out and play. If you could call dissecting frogs and deducing the new maid play. Molly watched Sherlock turn and lean against the door, sliding down to sit on the floor. One errant year trickled down his face and he quickly wiped it away. The floor creaked behind the door, and Sherlock turned his head, looking at the frame, a bittersweet smile hung on his lips.

"Do you want to play deductions?" He asked quietly. He almost laughed then, shaking his head. "Doesn't have to be deductions of course..."

Slowly, the door opened. Mycroft stood there, hands clasped behind his back. Behind him the newspapers from that day were scattered across the desk. Headlines declaring Sherlock Holmes a fraud, a kidnapper, a murderer. The articles that slandered his brother's intelligence hurt Mycroft the most. He had no doubt that as the elder sibling, he was the smart one. But Sherlock was his brother and he did in fact, have a far grander degree of intellect than the greater population.

"We both know I'd win." Mycroft said, looking down at his brother on the floor. Quickly, he got to his feet.

"I'm counting on it." Sherlock replied. Mycroft stepped aside, letting them pass into his office. There wasn't much time left, and Moriarty was already ahead of them. But if anyone could stop him, Mycroft Holmes had no doubt it would be his brother...with a little of his help, of course.