Father helped with Sherlock's studies.
He was full of paternal pride when Sherlock, aged 5, could calculate, almost instantly, any multiplication Father would demand of him.
Father called 5-year-old Sherlock his little "calculator machine" and he revelled in his success.
Calculator Sherlock was content.

Mummy nurtured Sherlock's musical talents.
She was glowing with maternal love as Sherlock, aged 10, played, from memory, her most favourite violin piece, having learnt it only 2 days previously.
Mummy called 10-year-old Sherlock her little "musical machine" and she beamed with delight.
Musical Sherlock was motivated.

Mycroft guided Sherlock to become a man.
He showed restrained sibling admiration as he watched an adolescent Sherlock learn to control his sentimental side and repress his emotions.
Mycroft called adolescent Sherlock his "narcissisticmachine" and he reminded himself to keep a watchful eye on him.
Narcissistic Sherlock was detached.

Lestrade gave Sherlock a purpose in his adult life.
He was openly imp
Lestrade called Sherlock his "crime-fighting machine" and kept him busy and distracted.
Crime-fighting Sherlock was stimulated.

John made Sherlock human.
He showed genuine pleasure as Sherlock showed off his brilliance and developed a level of empathy for others.
John called Sherlock his friend.
When John called Sherlock a "machine", it wasn't said with pride, admiration or love.
It felt wrong, agonising, confusing, hateful.

Sherlock was no longer content, motivated, narcissistic or stimulated.
His calculations were incorrect, his music discordant, his emotions raw and his deductions slow.

And so, as he stood on that ledge and tried to explain to John that the Sherlock he knew was "a fake", he wasn't lying.

Sherlock had always been somebody's "machine".

He didn't know how to be anything else.