Hi everyone! This fanfic is about incidents in the Holmes brother's pasts, and how they caused moments in the series. Warning: contains mentions of the death of a pet and some mild spoilers for 1x01. The opening and ending paragraphs contain phrases from the BBC series, I do not own these.

John stared into the intimidating stranger's face, 'who are you?'

The mysterious man replied with an expressionless face. 'The closest thing to a friend Sherlock Holmes is capable of having: an enemy. An archenemy, in his mind. But, I worry about him, constantly.' John opened his mouth to retort angrily, but Mycroft Holmes was already far away.

'Sherlock?' No response. The solidly-built teenager knocked repeatedly on the door. Mycroft prepared to put his whole, and rather sizeable, weight on the wood to force it, but just as he did so the seven-year-old opened the door reluctantly. Sherlock giggled as his big brother fell to the floor with an undignified thump!

'What it is Mycroft?' Sherlock turned away, so Mycroft wouldn't see the not quite dry tears on his round face. He pretended to fiddle with Redbeard's collar for a moment, then bent to kiss his furry head, hoping his dog-come-pirate's russet mane would wipe his eyes dry.

'You know what. I'm sorry, Sherlock.' Mycroft reached for Redbeard's collar but the young boy held on. 'Where do mummy and daddy want to take him?'

'To the vet. He needs urgent treatment, he is in a lot of pain, but he will be home soon.' Mycroft clenched his fists, begging his last words to be true. He knew where Redbeard was really going, and that Sherlock would never see him again.

'Okay.' Sherlock would only believe Redbeard was going to be safe when his brother told him. No one else could reassure Sherlock like Mycroft could. 'Until then, will you be my first mate, Mycroft?'

Mycroft let a small smile tug at his lips. 'Maybe. But you know I have to go back to school in a few days?' Mycroft boarded at one of the most prestigious boys' schools in England, while Sherlock was still in Primary School.

'Yeah…but that's still enough time to conquer the Evil Pirate Cut-Throat! He took first mate Redbeard hostage, but on Thursday crew members Mummy and Daddy will retrieve him from the Vet Dungeon!' Mycroft smiled sadly, watching Sherlock running around the room brandishing a tinfoil sword. If only he could always be so innocent…

'You promised! You said he would come back!' Mycroft knew that their parents had broken the devastating news to Sherlock the minute he heard the front door slam. He had told everyone he wanted to stay at home to work on an essay, but it was really because he couldn't bear seeing Sherlock's face when they took Redbeard, not knowing it was the last time, forever. He hadn't bothered to lock his door, he knew trying to stop Sherlock's fury would only make him worse. The thin body hurled itself through the door and threw an angry kick at Mycroft's chair.

'You promised. You lied to me…' The terrible realisation hit Sherlock like a truck, 'You LIAR!'

Mycroft couldn't stop Sherlock as he watched him tearing at the curtains, banging the walls, ripping up papers on his desk, he couldn't move. The pain and hatred in Sherlock's words stung like ice.

'I thought it was for the best…I thought it would be easier that way.' Mycroft mumbled, all pomp and confidence gone.

'I hate you! I hate you, Mycroft! I hate you all!' His own little brother, hated him. Hated him.

Mycroft left for school two days later. His last view of Sherlock was of him playing Pirates all alone in his tree house, swearing to God he would die before he let his archenemy the Evil Pirate Mycroft beat him.

'An enemy.' John and Sherlock were relaxing in Baker Street, John having mentioned his encounter with the strange man.

'Which one?'

'He said you were archenemies, at least in your mind.' Sherlock remained silent, thoughtful.