John rolled his eyes as he came to an abrupt stop just yards from 221B. The pretty brunette smiled as she stepped out of the car. For a moment John remained on the pavement before sighing heavily and getting in.

"Again, you could just text," he stated, staring ahead as the car made its way along Marylebone Road in the busy late afternoon traffic.

Mycroft smiled but gave no reply.

"Where are we going?" John casually inquired as he gazed out of the window, watching as they edged their way past Madame Tussaud's.

"To see an old friend," came Mycroft's drawling reply.

The car crawled along into the borough of Islington and John had to wonder if it would have been quicker to walk as the afternoon bled into the evening rush hour. They could not have travelled more than two miles in the 28 minutes he had been in the car as they turned off Pentonville Road and into King's Cross Road. Noting the name of the road as they pulled to a halt outside the Georgian town houses, he realised he was unfamiliar with this part of the city. "Claremont Square," he murmured to himself as the driver switched off the engine.

"And who is this friend?"John frowned, as he turned to face Mycroft who sat beside him, cross legged, making no moves to exit the car.

Mycroft smiled. "Heir to the most noble and ancient house in England." he replied, somewhat cryptically.

John's frown deepened as he looked away, eyes darting in confusion. "Well I don't think this is Buckingham Palace this time," he remarked sarcastically.

Mycroft chuckled. "No, so you won't be taking any souvenirs from this visit," he replied with a knowing smile. "This is the home of the heir to the highest aristocratic seat in all of England."

"Again, still not Buckingham Palace," came John's chuckled reply as he sat completely baffled.

"Wizarding England." Mycroft whispered with a twinkle in his eye.

.

"I am starting to wonder if perhaps you and Sherlock share some of the same habits," John remarked, jogging round from his side of the car as Mycroft crossed to the pavement outside the little terrace. John looked up and read aloud the name plate.

"Grimmauld Place. Okay, now I know we are in a twilight zone because Grimmauld Place is not in Islington, it's the other side of Regent's Park." John stated, his mind reeling.

"Yes, you see but this is the Other Grimmauld Place," he drawled, giving John a curt nod. "Note the houses."

"What am I looking for?" came Johns confused reply as he stepped forward, squinting at them. "They are all identical."

"Are they?" Mycroft responded, half amused by John's failure once again to see.

"Wait, there is no number 12." John replied, turning back to Mycroft. "But that…" he whipped back round at the houses. "But there is a number 13."

"And what is remarkable about that?" Mycroft pressed, as John puzzled.

"British superstition. Most roads do not contain a number 13, they skip from 12 to 14," John stated. "I still do not understand."

Mycroft chuckled. "Number 12 is there John, you just have to observe," he explained, stepping forward and heading up the steps of the house in front of him.

John's gaze darted from house to house, counting the numbers from one through 11 and 13 through to the end of the terrace. Number 12 was definitely not there. He then counted the gates and found he had a gate too many if number 12 was indeed missing.

"It's an illusion," Mycroft stated as he reached the front door, his back turned to John who had given up and jogged up the steps to stand beside him. He looked up as Mycroft straightened the knocker, realising the door had no number. His mind must have skipped it out. How bizarre, he thought as he watched his companion lift the knocker to rap on the door.

.

The redheaded woman stood before them confused, her complexion paling at the mention of the man's name. She turned and called over her shoulder, "Harry, could you come out here please?"

She stepped to one side as the dark haired man came to the front door. "Can I help you?" he asked, his tone measured but polite.

"We are here to see Mr Black." Mycroft replied, his stoic expression betraying nothing as John shifted his weight uncomfortably, as he watched the exchange. Something was off, but he couldn't put his finger on what.

"You had better come in," he man replied, opening the door wider, allowing them into the hallway. His wife motioned for them to enter the drawing room to their left, watching as the pair filed into the room silently.

"Can I get you some tea?" she asked, nervously. John presumed the question was more of a reflex than a gesture of hospitality. "No thank you, " he replied, smiling, as he attempted to calm her nerves.

"I am Mr Harry Potter," the young man began.

"I am aware of who you are Mr Potter." Mycroft smiled as he crossed his legs. John turned slightly in the seat beside him. "You are?" he quietly questioned. Mycroft replied with a slight nod.

"And I am aware of who you are, Mr Holmes." Harry replied, fixing his gaze on Mycroft who gave a small chuckle.

"Well, if someone could explain to me, that would be helpful," came the voice of the redhead beside Harry. John looked across at her, noting that she seemed quite furious as to the intrigue.

Harry placed a reassuring hand on her knee. "Ginny, this is Mycroft Holmes," Harry told her, his gaze returning to Mycroft. "His brother is a friend of Hermione's."

The corners of Mycroft's mouth twitched as her taut smile threatened to break. Ginny looked startled. "What do you mean? And what does this have to do with Sirius?" she asked, darting a glance over at Mycroft. John glanced around at them, bewildered by the conversation. "Er, I am sorry, but Sirius?" his gaze fell on Mycroft.

"Sirius Black, Heir to the Most Noble and Ancient House of Black, godfather to Mr Harry Potter, member of the Order of the Phoenix and agent of Her Majesty's Secret Service."

John watched as Ginny's eyes widened at the revelation that he was a secret service operative, but as her complexion continued to pale, he grew even more confused.

"It seems, Mr Holmes, that you do not keep a good record of your operatives. "

Mycroft's smile tightened. "And why do you believe that, Mr Potter?"

"Sirius has been dead since 1996," Harry replied, his green eyes betraying no emotion as he maintained eye contact with Mycroft.

John's mind reeled at the turn the conversation had taken as his eyes snapped to Mycroft who tutted quietly, giving his head a small shake. "More's the pity. We were rather hoping for his assistance."

"With what?" Harry's tone remained even.

Mycroft leant forward slightly, his smile returning as he drawled, "We need to get into 'Diagon Alley'."

.