Don't Tell. Never Tell.
The words 'Patient Confidentiality' weren't just words in the wizarding world, but a Binding Oath, not dissimilar to the Fidelius Charm. The secret was kept within one person; the Healer treating the patient. There was simply no way any Healer could reveal their patient's condition without the permission of that patient.
Normally, this was something Madam Poppy Pomfrey agreed with wholeheartedly. When it came to Harry Potter, however, it was something cursed. Harry Potter was not, unfortunately, the first, and she doubted he would be the last, abused child that she would have to treat. In these most extreme of circumstances there were ways of getting around the Oath, and the child's magical guardian: the victim's Head of House at Hogwarts, could be informed.
The magic involved in this was incredibly was incredibly complex and was almost alive. It knew when to allow such a breach of the contract. Unfortunately, as always, Harry James Potter proved to be an exception to the rule.
It was a long standing joke at Hogwarts that the Hospital Wing was Harry's second home in Hogwarts, but that wasn't the case in Harry's First Year. Even when Harry became the youngest Seeker in a century and it looked like he came mere millimetres from dying in his first match, due to a cursed broom. Most, young or old, would at least want a Calming Draught after such an experience, which Madam Pomfrey would've given without question. What Harry went through in his first game must have been beyond terrifying. Personally she thought it was a miracle he ever went near a broom again (then again, she had always considered Quidditch an overly dangerous sport).
But Madam Pomfrey didn't see Harry after the match. Apparently he relied on tea with Hagrid to calm him down. Not that she had anything against Hagrid but … still. And she didn't see him after that, after every scrape and illness, when he really should have seen her. Harry simply refused to come to the Hospital Wing. Occasionally he would grudgingly slip in for a Pepper Up Potion during the Winter months, when forced to by his concerned friends, but he never came close enough for her to perform a full medical check up (she wasn't an idiot: she had noticed the oversized, thinning clothes and his skeletal frame. She had seen it too many times before).
Then came the end of Harry's First Year, the Philosopher's Stone and Harry's three days of unconsciousness in the Hospital Wing. They had rarely had such near deaths in Hogwarts.
Later, she supposed she should have gone to Minerva McGonagall the instant she had actual proof of the abuse she had suspected, but she hadn't wanted to leave her patient for a second. Not when his condition was so unstable. She supposed, if she refused to let the constant guilt get in the way, she had made the right decision – if she had left him to find Minerva; he might have died.
It was a bitter pill to swallow though. When Harry woke up his eyes widened immediately. He must have realised from the pitying and sympathetic look on her face that she knew, and with extraordinary strength, both for his age and for the fact that he was still extremely weak, his hand shot out and grasped her wrist,
"Don't tell. Never tell," he choked out,
And that was it. She was bound. Bound by Oath, an oath reinitiated by an eleven year old boy she was trying to help. She nodded. There was nothing else she could do.
She saw him much more after that, and she liked to think he was beginning to trust her; she certainly had a fondness for him. She doubted it though: she knew she did not have the easiest of temperaments, and she knew that Harry would be automatically suspicious of those around him, especially adults, and especially those in positions of authority.
Normally, the fact that most of the children didn't like her didn't bother her. It mattered much more to her to get them well than to get in their good books by letting them run free, after all. But as always, Harry was the exception to the rule: he had somehow managed to worm some small hole into her heart.
Harry did, however, acknowledge what they both knew, sometimes. Never openly, or out loud. Never when there was any one else around who might have had a chance at interpreting the odd words and looks. The way he would look down in almost shame and the way she would, in her own way, tell him it wasn't his fault. It was theirs. He would show her the odd injuries when no one was about, even his closest friends.
In the years that came Harry gradually opened up to Madam Pomfrey, but he still refused his secret to be shared with another living soul. All the while Madam Pomfrey grew ever more protective of the boy she had come to care for. She tended to all his injuries, both from his adventures and his abuse at his house. Harry refused to ever call it a 'home'. Eventually, she learnt some of his secrets (though, she suspected, not nearly all of them).
In the end he grew, left and fought a war. He lost so much, even died and came back, that Madam Pomfrey sometimes thought that the injuries from those he grew up with (she never learnt their names and he called them family, though she had heard from Albus that they technically were) must seem insignificant. But she knew that the psychological wounds received in childhood always left deep and lasting marks. As much as she hated to admit it, Harry Potter would never recover. She had failed. She had failed a patient, and she had failed a friend.
Harry came back occasionally, to give Defence Against the Dark Arts talks. After several visits he visited Madam Pomfrey in the Hospital Wing, hovering just on the edge of coming in. It took a while for her to notice him, as small and inconspicuous as he made himself. As he had always made himself. When she did notice him and waved him he gave a shaky smile,
"I never said thank you," Harry said, "for all that you did for me, for all those years," Madam Pomfrey knew he wasn't just talking about fixing his wounds,
"You never had to thank me Harry. Just let me ask you this one thing; why did you never tell? It would have helped you so much. You could have been taken away from those … people,"
"It wouldn't have helped me," replied Harry gloomily, "well, mainly. I suppose you're right, they could have taken me away from them, but I was used to not trusting adults. None of the teachers at my old school ever believed me. I suppose you're used to kids like that. The main reason though is that I realised that I was Harry Potter, The Boy Who Lived. They'd turn me into even more of a freak show than I already was, if they ever knew, and I couldn't stand that."
Madam Pomfrey nodded in sad understanding. She hated it, and part of her still wanted to tell, but she knew, as twisted as it was, that the best thing for Harry would be to keep his secret. For the first time she was glad that Harry had made her keep her Oath all those years ago. Harry had too much to deal with as it was.
