When is the doctor not the doctor?
The nurses hate him. John knows that, but he can't help it.
It's Sherlock lying in that bed, Sherlock so pale he blends into the flimsy sheet, so pale the bandage at his temple vanishes on his cheek. John asks about tests (probably unnecessary), demands to see Sherlock's chart (illegible even by his standards, what sort of hospital is this), and questions every word out of the other doctor's mouth. He clings to Sherlock's hand through it all, willing those mossy eyes open.
And John knows that the only thing worse than having a doctor for a patient is having a doctor's loved one for a patient.
But it's Sherlock.
None of them can understand that. None of them can understand the clutch of fear at seeing Sherlock take a blow to the head and crumple before John can get there, can interpose himself between that perfect mind and the falling pipe. None of them can understand the panicked litany in John's head: unconsciousness, traumatic brain injury, married to his work. None of them can understand what the loss of even an iota of functioning could do to such a well-honed machine.
All they understand is that he is not the doctor here.
When is the doctor not the doctor? When he's the boyfriend.