It started as a review for the wonderful Librarianmum's story 'I Could Write a Book' - if you haven't read it yet I recommend it, it's very good! Anyway, then the cheeky lady challenged me to write a story about a younger Mycroft and Sherlock being forced into a walking holiday. Fortunately she gave me free rein, and so this was the end result - a third story to add to my kid!lock universe.

"Come on 'Lock, it's not that bad." Mycroft called for the umpteenth time as his curly haired younger brother dragged his feet (quite literally) through the rough grass.

"It's pointless." He pouted. "Why did Mummy insist we go hill walking anyway? What use is it?"

Turning with a sigh Mycroft put his backpack down, checking that the ground beneath him was dry and free of anything nasty before sitting down to wait.

"Mummy worries that you spend far too much time indoors with your books and your experiments." He explained calmly, resting his arms on his bent knees and clasping his hands together.

"But you said I should endeavour to learn as much as possible..."

"Yes I know, I also said everything in moderation Sherlock – I could have foreseen this happening though, of all the words you learnt so young moderation was never one you understood."

The young boy pulled a face as he threw himself down next to his older sibling and peered interestedly at an ant carrying a large blade of grass.

"Can we stay here? I can study the ants and bees and things."

Sherlock squirmed as his brother reached out and ruffled his curls.

"I'm afraid not." Mycroft clamped his hand down on the top of Sherlock's head and forced him to look behind them.

In the distance he could see the tiny cottage their parents had rented for the week while their mother painted watercolours and their father wrote speeches to present to the House of Lords.

In the garden of the cottage a graceful silver haired figure could be seen standing still, facing the hill path.

"Mummy's watching, she'll only insist you come out again tomorrow, but if we do as she asks today you can at least plead fatigue." He waggled his eyebrows infuriatingly at the pouting child lying beside him. "And anyway, I have a surprise for you."

Grey eyes lit up as skinny limbs hurriedly sat up.

"What? Tell me!"

"I'll do better than that," Mycroft smiled fondly down as he stood and brushed grass from the seat of his trousers. "Come on Scallywag, I'll show you!"

With renewed energy the Holmes brothers set off once more up the hill, Sherlock covering twice as much ground as his older brother but generally sideways, finding small outcrops of rock to scramble over, tripping in his haste not to let Mycroft's longer strides carry him too far from sight.

As they crested the hill Sherlock gazed in wonder at the view ahead of them.

Perched on the other side of the hill was an old ruin, possibly a remnant from the days in in-fighting between landowners, not a castle, but not quite a house. Surrounding it were trees, mainly oak, but a few others had found their way in. It gave the countryside a magical quality.

Mycroft couldn't help thinking that if only Mummy would bestir herself this would make an idea vista for her to paint.

Sherlock on the other hand was thinking marauding Vikings, pirates, ghosts and buried treasure.

With a whoop of delight he sped down the hill, crashing recklessly through the trees and into the ruins. Trying to keep up as best he could without falling and hurting his pride as much as his body; Mycroft called after him to be careful.

"Watch out for loose masonry – and don't stand on any wooden flooring, you don't know how rotten it will be."

A distant "okay" was all the response he received. At last passed out of the woodland and through the ruined arch doorway.

With a 'pfft' of dirt rising at his feet a rock landed; and a cry of "Get back! You'll never take the castle!" assailed his ears just minutes before he realised his brother had utilised a willowy tree growing out of a wall and was using it as a catapult.

He grinned and dodged behind a wall, happy to indulge his brother.

Crouching down, Mycroft searched around for some clumps of mud – crumbly ones, less likely to hurt should he accidentally hit his target – and having found a small supply prepared to retaliate.

"Ahoy there Captain Sherlock! Surrender the castle or I'll loose the four pounders!" he lobbed the first of his unstable missiles and laughed as it disintegrated in the air, a cloud of dirt.

"Never!" came the giggled reply.

For almost an hour they threw or catapulted missiles to and fro, their shrieks and laughter echoing around the ruins. Pausing for breath Mycroft reached into his backpack for a bottle of water – it was a mistake. He looked up just in time to see his younger brother, all wild eyes and flying curls leaping at him from the crumbling wall.

"No!" he yelled somewhat redundantly, for the giggling bundle of humanity was already airborne, and it was all Mycroft could do to catch him and fall gracefully enough that neither was hurt.

"Gotcha Myc, you're dead!" Sherlock bounced up and down on his winded brother shouting gleefully.

"You…." Mycroft puffed, trying to get his breath back. "….are a little hellion. You're taking far too much pleasure in having killed me."

"I claim the treasure!"

Rolling off his much battered brother Sherlock raided the backpack, pulling out another bottle of water and two packets of sandwiches.

Handing one to Mycroft he sat with his back against the wall and heedless of the mud smearing his hands unwrapped his food and tucked in with gusto.

As they ate the older Holmes explained what little of the ruin's history he had been able to glean from the local guide books in the cottage. And when they had packed their rubbish back into the bag he led his younger brother round, pointing out the different architecture – proof that the building had stood and been extended over a long period of time, before finally being abandoned to its fate.

Getting his second wind Sherlock was soon off again, this time climbing through the trees, rivalling the dexterity of monkeys with the way he swung through the branches.

Always keeping his younger brother in sight, Mycroft gradually manipulated their journey, so that soon they were climbing out of the woods and heading once more towards the holiday cottage. They were almost within earshot of Mummy, still painting the cottage garden when Sherlock stopped and looked earnestly up into his brother's face.

"Today was brilliant Myc, can we do it again tomorrow?"

Mycroft smiled and assured the young pirate that they would go back as often as he wanted while they were staying in the area, but as Sherlock dashed off whooping and crowing at the top of his voice he didn't see the smile turn sad and forced. And Mycroft didn't know how he was going to break the news that within days of their return home he would be leaving for Oxford University, and leaving his beloved little brother behind.