*Note: In which the scientific method is very sexy.

Afterwards, when the room's stopped spinning, and sounds of passion have quieted into a tranquil silence, they talk.

Sherlock has collapsed on top of John's chest, and situated his head neatly on his blogger's heart, peacefully listening to the calm and steady beat.

John hasn't felt his own heart beat in years.

"So..." John nips at Sherlock's earlobe, which triggers a moan from both men. "Was your experiment a success, or..."

Sherlock's eyes flutter open, and he struggles to find his way out of the translucent, orgasmic haze he's lost in. His cool, grey eyes move up to meet John's green and he says in a voice so sexy that John thinks he might explode, "Need more data," before he resumes senselessly snogging John.

They experiment all night.

Irene's nickname for Sherlock no longer applies. Both of them couldn't be happier.

Sherlock creates a special room - no, not a room. A temple - in his mind palace where he stores the experience. There's a shrine for John Watson, and Sherlock intends to worship him every chance he gets.

Sherlock makes a list of everything John likes:

(He does it very scientifically. Trial and error. Testing theories, hypothesis, and never, ever jumping to conclusions.)

1.) Subject prefers topping over bottoming but is open to persuasion if motivated.

2.) Subject enjoys being called 'Captain' and 'Master'.

3.) Subject enjoys referring to partner as 'Pet' and 'Mine'.

4.) Subject enjoys it when experimenter plays with his tongue.

5.) Anything with hair. Subject likes ANYTHING with hair.

6.) Subject enjoys biting, light bruising, and other modes of torturous pleasure.

7.) Subject wears red pants.

Sherlock would thing John's strange, newfound tendency to lead everything if he wasn't too busy being distracted by the wonderful new variety of things a John can do with his mouth.

John never realized science could be so sexy.

Later, when Sherlock is exhausted and has slipped into a deep, blissful, dreamless sleep, John picks up his phone and makes the call.

There's no turning back now. But all John wants to do is replay the last night over and over in his mind for eternity.

'I owe you a fall, but I'm fallin' for you.'