Harry didn't have the ability to heal people in the books. (Why not, I wondered? He needed it.)
He doesn't have it at the beginning of this chapter either. :D Enjoy.
~Multi-Faceted~
VII: Healing
Albus took Harry by the arm, figuratively and sometimes literally, and taught him healing spells little by little. The boy knew that he was being taught so he could save himself, for once—so he could deal with any minor injuries until help could arrive—but the time with his headmaster was still his, was still precious.
Practice was harder. Albus wanted Harry to use him as a test subject, but the latter wouldn't allow it—would even go so far as to take Albus's wand—The Elder Wand!—from his headmaster if the blue eyes gained a suspicious glint. Likewise, Albus roared in protest of Harry harming and then healing himself.
Both refused to involve anyone else—so they were at a standstill, until the day that Albus pulled his wand, Harry reacted too slowly, there was a loud BANG, and suddenly Albus's shoulder was bleeding too quickly, and the man's teeth were clenched to ward off some of the pain.
"Albus!"
"I am f-fine," Albus managed. "I… oooohhh…" He moaned in pain again. "I merely… ouch… miscalculated."
"Miscalcu—WHAT were you thinking? What did you hit yourself with, that you're bleeding so much?"
"It—was—an accident," Albus panted; he watched Harry stare at him, made dumb with the force of his rage. "Spell was—unintentional."
"I'll say," Harry snarled. He yanked his wand out of his own robes and severed the shoulders of his mentor's robe with a hastily-muttered "Diffindo", so as to better see the gash. Albus did not protest—the robes weren't his favorite.
After a few moments, Harry whimpered with relief—the wound wasn't as bad as it could have been. Unthinkingly, he waved his wand over the area, muttering when necessary—his attention was focused on glaring at his mentor.
"Don't—Tergeo—EVER try and hurt yourself again," Harry scolded, still fuming. He tapped the spot, and the older man flinched as the bone rearranged itself.
Albus almost had to bite his tongue to keep from pointing out that, had Harry tried to draw his own blood and succeeded, he himself would not have been able to stop and see reason, let alone take time to heal Harry. The boy's blood made him crazy that way.
Instead he murmured: "It… is better this way. At most, I will have a decorative new scar like yours."
"'A decorative scar'? You're bloody lucky I can even heal this!" And he set to it.
Albus, ready to reply, to scold Harry for bad language, stopped as he alone realized the full implications of his protégé's words. He smiled warmly, and watched mutely as Harry expertly tended to his wound in a way he couldn't have done six weeks before. He chuckled, too, when the boy was done.
"Thank you, Harry. I feel much better."
"You're welcome," Harry replied, a little crossly—and at that moment, the whole of what he had just accomplished fell on him.
His green eyes were wide with wonder, and he stared down at his pinkish hands as Albus examined his own good-as-new shoulder while roaring with laughter.