Leonard is twelve the first time someone dies under his hands. Granted, that someone is a horse, named Lola, that was old to begin with when she leapt the fence as he and his father tried to get the horses inside during a thunderstorm and bolted into the forest.

They find her the next day at the bottom of a small ravine, both front legs broken, chest heaving and whickering softly in pain. His father leaves him with her while he goes to get his shotgun. Leonard gets down on his knees in the mud next to Lola, sliding close, rests one hand on her side and runs the other through her mane and tries not to look at the twisted angle of her legs.

Lola dies just as his father comes back, her last breath leaving her in something reminiscent of a sigh. He sighs as well and leaves again—this time to call a few friends who will be able to help them get her out of the bottom of the ravine. Leonard stays where he is, feeling her muscles go rigid and the warmth leave her skin.

Even at this age, he is well and determined to be a doctor. This is the first time someone dies under his hands, and regardless of the fact that there's nothing he could have done, he makes a child's promise to himself in that moment—it won't happen again. Not on his watch.

It will, inevitably, but less often than most, because the next day Ashton from the local antique store will call and tell him that someone brought in another box of books, medical textbooks, and they're his if he wants them because there's no way Ashton will be able to sell them. He'll go and he'll fall in love, with these thick books with the words he scarcely understands but wants to more than anything, and the old ink drawings, all the knowledge perhaps slightly outdated but it's a start, and he'll lug the box home and spend hours poring over each and every one until he reaches the bottom and finds one not like the rest, a little book bound in buckham with well-thumbed pages and written mostly in a language he doesn't know, some strange trailing script that looks vaguely like old Arabic.

Except there will be pages he can read, near the front, pages in English that speak of Powers and Choices and an eternity-long Battle and magic and he thinks it's a joke, a children's book that whomever brought in the medical textbooks either didn't realize made its way into the box or just decided to pack in with the rest, but he finds he can't stop reading because this magic, this wizardry, he wants it to be real, more than anything, because it's offering him everything he's ever fiercely wished for—offering him what he begged for as Lola lay dying in front of him the day before. The ability to fix, to heal, to save, to be enough, only on a level grander than he's ever imagined.

(Starfleet is scarcely out of the galaxy and here this book is talking about Andromeda like they're our next-door neighbors—)

It's heady, it's breathtaking, it's almost too good to be true—but then he turns a page and finds a single block of plain-type text, fantastical in its utter ordinariness.

It's not too unlike the Hippocratic Oath. An Oath to first and foremost, do no harm.

An Oath to protect everything that lives and grows, in the name of Life itself—to protect the whole Universe from its inevitable ending—he can think of no higher calling.

Oh, it terrifies him, too. He's twelve, and here is an Oath—and he knows oaths are serious things, but something tells him there is none more serious than this—and it's telling him that he must forsake fear for courage, death for life—a twelve year old hardly thinks of dying, let alone laying down their lives for others.

But then he thinks of Lola, again, of the feeling of her struggling for breath, of the pained, resigned glaze in her eyes, of people dying the world over, the galaxy over, for stupid reasons every day, and he thinks, this is the chance to change that.

If it's real. Which he's becoming less and less certain it's not.

Where's the harm?

The worst that can happen is nothing. The best that can happen is…everything.

In the violet dusk of a Georgia summer evening, Leonard McCoy leans close, breathing in the scent of pages that something tells him have seen more than their appearance belies, and reads the words of the first oath he'll take in his life—but not the last—scarcely noticing as the dusk and the fading sunlight lean close and the chirping of the crickets and the rustle of the wind fades away and the words he speaks echo more than is feasible off the old oak panels of his bedroom.

"'Til Universe's end," he whispers, and it feels less like an ending, and more like a beginning.

(Two days later, he'll nearly fall off the fence he's fixing—or half-fixing, because his manual is propped against a post beside him—in surprise when a young foal wanders over and whickers, clear as day, "Where's Lola?")

(Three weeks later, he'll face down the Lone Power, the Kindler of Wildfires, in his own guise when a blaze of fire not of this Earth, or any planet known, threatens to destroy the forest—an Old Forest, of power beyond measure—and half the state along with it. He wins, narrowly, and the fact that he nearly turned his back on his Oath, nearly turned tail in the face of Death himself, doesn't matter, because he didn't, because he saved what he would never have been able to save before, and that's all he's ever wanted.)

(Twelve years later, after more assignments than he can count and more failures than he'd like to admit, because no one is perfect, he will order everyone out of the room of a young woman who is sure to die within the hour if nothing is done, and he will hold the breath in her body with sheer force of will as his magic knits bone and muscle and skin just enough for her to live, should she desire it. And he knows she does. Even if she doesn't yet know about the small knot of light low in her belly, her heart does, and as he collapses into a chair, chest heaving, the gash across his palm healing, he can hear it in his ears as the wizardry fades, beating strong and true and he smiles because he can't fix everything, can't save everyone,

-a truth he'll soon enough find applies even to himself—

But in moments like this, he feels like he could, and it's enough.)

The Young Wizards fandom on tumblr delved into a thing recently - the WizardTrek 'verse. Check out #wizard trek or #wizardtrek there if you would like to see what other works people have written thus far :)