On this day it was very boring on Earth, in Europe, in Great Britain, in London, in 221b Baker Street. The sleepy afternoon-sun stretched its golden rays weakly in order to reach John, who had just leaned back from writing for a moment. His flatmate Sherlock seemed to be completely absorbed into his newspaper until he suddenly disturbed the dust that was peacefully dancing in the sunlight by yelling “BORING!” into the silence of the afternoon and throwing down the paper in disgust.
John just rolled his eyes but couldn't stop a small smile from escaping. “That would imply that you had a drill, but I wouldn't put that past you. You like doing all kinds of strange stuff; blowing up the apartment, massacre the walls with bullets, putting partly decayed heads into our fridge...” 
There Sherlock interrupted him. “John, the refrigerator slows down the decomposition considerably, meaning its usage is only sensible – I will never find out why you deign it suitable to store plants.”
“Those plants are called vegetables and they are, by the way, good for your body and health, Sherlock.”
After hearing these words Sherlock suddenly stood up and went to the fridge with five long strides, where he opened the door so quickly that its hinges protested. “What an interesting theory! John, how about from now on you only eat plants?”
Offended, John closed his Laptop. “What is that supposed to mean?” The corners of his mouth were twitching slightly and he was frowning. This expression would have warned anyone to tread lightly – but not Sherlock, because the detective was way too busy studying the vegetables and gesturing wildly. “By consuming this produce you could revolutionise your alimentation.”
John stepped over to his flatmate, crossing his arms in front of his chest. “I am aware of this fact. What I am not aware of is the reason why you think I should change my 'alimentation'”.
Apparently unperturbed by Johns offence (or maybe merely unaware of it), Sherlock continued with his explanation. “Since you are now of an pensionable age and receive less exercise, you are more susceptible to weight gain and would benefit from a change of diet.”
These words were like a slap to John's face. He opened his mouth to say something, but immediately shut it again when he realised that there was nothing he could retort in the face of such absolute impertinence. After some more desperate attempts to form a sentence that made John look like a (slightly podgy) fish, he turned on his heel and slammed the door to his room shut while Sherlock looked on, slightly confused.
“Small brains,” the consulting detective sighed. “What have I done wrong now?”
While he was waiting for the pensioner's imminent return and the following explanation, Sherlock assessed the contents of the fridge. His gaze fell on something he couldn't quite place – it was small and wrapped into a thin plastic bag. Frowning, he retrieved the bag from the back of the fridge and placed it on the counter. There were white, cylindrical sticks with brown caps inside – probably the Psilocybe cubensis, also known as “magic mushroom”. He was aware that the effects could be quite intoxicating, but conducting one's own research was never wrong. Considering this fact, Sherlock had to concede internally that perhaps keeping a “plant” in the refrigerator wasn't too infantile a thought process.
When the ninth stair creaked, a big smirk began to form on Sherlock's lips. “Let the party begin,” he mumbled into his non-existent beard.
Suddenly, the door banged against the wall. “What is your problem, Sherlock?! You invite me to-,” Mycroft breathed in deeply in order to be able to yell more loudly. “Come on in, the door is open,” Sherlock used the pause calmly.
“TO TEST DRUGS ON YOU!” Mycroft continued to scream, “And you expect, you really expect...”
“Alright,” Sherlock interrupted his brother, “Now we all calm down for a second and listen to our little brother, who is in the possession of a far over average intellect.”
Mycroft's gaze just continued in its endeavours to murder Sherlock.
“I changed my mind,” the detective explained nonchalantly. What his older brother didn't know was that Sherlock instead intended to test the drug on him, John, as well as Fred Lestrade – the latter of which had listened to his invitation to dinner with a confused and shocked expression. Sherlock had taken this as acceptance.
“Great. So my presence is no longer required.”
Even before Sherlock could protest (and he was quick at protesting), Mycroft jerked open the door, staring directly into a already totally overwhelmed face.
“Inspector,” he addressed the completely petrified Grag, who had still raised his hand for a knock. Then Mycroft smiled. “Great that you could make it. I was just about to open the door for you. Do you have any plans for after your appointment with my little brother? I have to show you something very important.”
The inspector shook his head dumbly. Mycroft's presence seemed to have left him barely able to function. The man still blocking the door was pushed aside by his younger brother. “Now, come on in, Jack. You both can talk about your date at a later date.
George started spluttering, while Mycroft's smile gained a bit of a sardonic edge. “And where is your date? Have you unconsciously insulted him once again?”
“Were you not about to go?” Sherlock snapped back, turned around gracefully and stepped over to the table where the food was waiting.
Just as he was about to deliver his excellent but brief speech, John stepped out from behind the door to his room. He blinked at the light and his hair was in the worst disarray imaginable. This was somehow very... cute?... the detective noted, confused. Even cuter was the red blush dusting his flatmate's cheeks as soon as John realised that there were three pairs of eyes staring at him.
“Wrong door,” he declared into the completely silent room and as fast as he had appeared, he disappeared again into his room, while Mycroft and Gale were still staring at the door, which John had closed once again.
By clearing his throat Sherlock regained their attention.
“Recently I became aware of a feasibly interesting case.” He gave both of the men an intensive stare, before he started walking up and down behind the table as if in deep thought. “In this case a rat teaches a man how to cook,” he paused here dramatically, so Christian and Mycroft could deal with the shock. Unbeknownst to him, both knew the story “Ratatouille” and only exchanged a meaningful look. “And so I thought,” Sherlock continued, almost purring,“I thought that maybe I could cook for you sometime.”
The room was completely silent once again. Everyone – even John who was now standing in the door frame – looked at Sherlock, utterly flabbergasted.
“John, call an ambulance,” Mycroft finally ordered after some seconds of only the wind blowing against the windows, but John just rolled his eyes and sat down in front of a plate filled with noodles and mushrooms, sipping a cup of coffee. “Don't be so dramatic,” he answered, “Sherlock is... also... human and...” he seemed to realise how bizarre his statement had started to become and continued talking more and more slowly. “He also wants to do something nice for his... friends.”
When hearing these last words, Sherlock shot John such a freezing gaze, that the pensioner resigned himself to silently drinking his coffee.
Graig cleared his throat tentatively, his eyes glued to the elder Holmes-brother. “Err... I could call the ambulance for you.” Mycroft's forehead creased slightly, so the inspector rushed to continue.“Only if you want me to I mean.”
“It would be an honour,” Mycroft smiled and Grant immediately fished his phone out of his pockets. “Yes, hello... 221b Baker Street, Inspector Lestrade speaking. We need-” he stopped suddenly. “Look here, I am calling on behalf of Mycroft Holmes and-” he jerked back from the speaker when the person on the other end started yelling. “This is now the 10th time this week alone and no, he is still healthy, although I can't say the same about YOU! Your friend Mycroft and you should perhaps come for a visit! Turn right to get to the psychiatric ward! Have a nice evening!”
With these words the receiver on the other end was slammed down loudly and the call ended.
The inspector stared at the wall and its bullet holes, white with consternation. The man had screamed so loudly that everyone in the room was now aware of his opinion of them.
Mycroft fixated John, who had significantly recovered from Sherlock's glacial look. “Then you have to bring him to his senses! He has never done anything nice for me before and I don't know how to handle this situation.”
While Mycroft was still trying to make a decision, Sherlock was already pushing him in the direction of the table. “The only thing you need to handle right now is your cutlery,” he asserted. 
As soon as he had pushed his brother into the chair, Gavin took a seat and looked at the food piled up in front of each of them sceptically.
After some seconds of everyone silently assessing their plates, John dared the first advance into the potentially hostile area that was the plate. Mycroft and Matt watched with big eyes as he tentatively tasted the meal by using only the tip of his fork. Then he suddenly became deathly pale: “This is...”
“Horrible?” Mycroft guessed.
“Really bad? Poisoned?” as Mycroft continued to use gradually worse words, one could again hear angry shrieking from the proximity of Gus' hand, he had conveniently and inconspicuously placed under the table. Supported by an especially loud “Deranged!” John found the all-encompassing and perfectly descriptive word: “...good,” he finally stated, seeming fairly bewildered and maybe even a bit disturbed.
Craig was so shocked that he promptly hung up.
Mycroft chocked even though he hadn't even eaten anything yet, which resulted in him gulping for air in a fight against death, from which he was only saved by Gale's valiant intervention; he clapped the older brother on the back lightly.
As soon as Mycroft's fit was over, he took a deep breath – partly because he could and partly because he needed air to execute his diatribe effectively – and had to admit that the food at least smelled nice, John hadn't been lying.
“This is just unacceptable!” he still yelled, gasping for air. “Sherlock, if you are planning on assassinating me, then kindly try harder!”
Sherlock rolled his eyes, he was annoyed by his brother's melodramatic performance. “I obviously do not have to try much harder. Planning your assassination would be thoroughly monotonous and insulting my intelligence,” the detective stated while pulling a small notebook out of his pockets and intensively eyeing the three men before him.
“Now for a different question,” again Sherlock halted his words to lend them a more dramatic backdrop. Gabe, John and Mycroft internally started going through all kinds of questions the consulting detective could be asking every second now. How tall is the Eiffel Tower? When are you going to the hairdresser's, John? And can you house people in a tent? 
But what he actually asked exceeded even their boldest expectations.
“Actually, how are you doing, brother dear?”
Judging by Mycroft's facial expression, the third call to emergency services in the space of five minutes was imminent. A new record. At least for the day.
But instead of taking this opportunity to pat down Gaius' pockets in search of a phone, Mycroft leaned back slowly, pressing his fingertips together so they formed a small tent. “Sherlock, be honest..,” he stuttered for a moment, unsure about how to continue, “are you dying?”
Sherlock didn't answer at first, but he wrote something in his notebook.
“I am merely a very interested human being.”
John burst into loud laughter, no doubt due to the last two words, but he was immediately silenced once again by another cold look the detective threw at him.
“Mycroft, good God! How. Are. You?!”
His brother frowned and started seriously thinking about how to answer the question. Well, he was feeling like always but Sherlock had gone to all the trouble of cooking food for everyone and had now also asked him, Mycroft, about his well-being.
“Well, actually I am-,” he had to clear his throat, suddenly feeling insecure, “I am happy.”
Sherlock froze completely for a second. In the next he started scribbling into his little book as if possessed and Mycroft could only decipher something about a “very intense effect” from where he was sitting.
“Do tell what you are doing there.” Mycroft was at Sherlock's side in the space of a heartbeat and tried to rip the notebook out of his hands. But Sherlock defended it valiantly and after a minute of this, a grim war had broken out, which John curiously watched from his vantage point that was the dinner table.
While John was simply watching, Mac had joined the fight and was trying to support Mycroft, but the only thing he succeeded in was hugging the elder brother and groping him from head to toe while uncontrollably flailing his arms. This seemed to impede Mycroft critically, but he didn't complain.
Somehow, Mycroft was finally able to bring the book into his possession. Everyone was looking over his shoulder curiously, except for Sherlock, who was staring at him, indignation and defiance in his eyes.
“What is that supposed to mean? Experiment?!”
John, who had misplaced his glasses specifically made for pensioners asked Mycroft to read the notes out loud, while Sherlock crossed his arms in front of his chest and sullenly slunk off towards the sofa.
Mycroft cleared his throat and read:
Experiment Psilocybe cubensis
John: no change in weight – unfortunately
Mycroft: very intense effect – suddenly able to feel happiness (possibly mind-altering vapours)
“Congratulations, brother dear, you can read,” Sherlock observed drily.
“Okay, great. What is decidedly not great is what I am reading there!”
Sherlock seemed to think for a moment. “Hmm... Letters?”
Just when Mycroft's fingers were starting to tear the paper with their tension, John stepped before him with raised hands, effectively shielding Sherlock. “Now, I am sure that there is a rational explanation for this. Right, Sherlock?”
The detective raised both his eyebrows. “Of course. Experiment is a Codeword.”
“For what? Extremely perfect inscenation of monumental and endless tomfoolery?”
Mycroft's hands started dangerously shaking again and John shoved his elbow into Sherlock's ribs inconspicuously.
“Okay, brother dear, I found some mushrooms in the fridge and wanted to test the effects of these drugs.”
Before Sherlock could react to Mycroft's angry exclamation, John acted on his own initiative to avoid a bloodbath. “Yes, mushrooms – they make me so happy it is almost like a drug. Am I right, Sherlock?”
The detective answered his flatmate's forced grin only with an empty stare and stony silence, until John shoved his elbow into his ribs once more.
“Naturally. And because it is so... important to me to make John happy, I decided to make mushrooms for him with a totally new recipe. Basically as an experiment.”
Mycroft just stared at him in disbelief until Jerry shrugged. “Seems plausible.”
“Plausible?!” asked Mycroft, blinking dumbly.
“Yes, you know; logical, comprehensible, coherent, convin-”
“I know what plausible means. How can you believe such a fairy tale, Gre- Lestrade?”
“Err...” the inspector seemed to be mentally stuck on Mycroft's last words (mainly the fact that his name had been almost mentioned), but he recovered quickly. “No, no, I would never believe such a story, I am a policeman after all, ha-ha. I just wanted to see... how you would react.”
“What do you think how I would react to such stupidity?! Am I supposed to throw my hands in the air and rejoice while screaming 'Yes, my date is insane!'”
At first, Mycroft didn't even realise what he had just said there.
“Date?!” John finally asked.
While the colour of the elder brother's face was still changing from an angry red to an aghast white, his hand was already grabbed securely by Gandalf's as he was being dragged out of the flat backwards.
“Have fun with the rest of your date!” John called after them and shortly before the front-door downstairs closed he could hear a muffled “Same to you!”
John was completely baffled by this answer and did, what he always did when he was unable to recognise a reason behind an action (though this action was murder in most cases) – he turned to his flatmate. “What is he talking about, Sherlock?”
A mischievous grin stole itself on the detective's lips. “I do not have faintest idea.”
In the resulting comfortable silence the two were only looking at each other. Sherlock was still wearing his grin, which gradually changed more and more to an honest and warm smile. He seemed to glow from the inside. He was the most beautiful, the most radiant thing John had ever seen.
Sherlock's deep voice took him out of his silent admiration. “And you... want me to make you happy?”
John felt an answering smile tugging on his lips and, using the excuse to scratch his neck, he averted his eyes from Sherlock. He was scared that otherwise he would never be able to free his gaze (or other parts of his body) from Sherlock's form. So he studied the floor closely. “Well...”
After some more moments of sheepish silence, a warm hand suddenly reached to his chin and John's surprised eyes met Sherlock's blue ones. In the depths of the detective's gaze unfathomable emotions danced and John wanted to get to know every single one of them.
On this day John found out that Sherlock's real smile did not only look warm, but that it also felt exactly the same way.