Disclaimer: Obviously, I don't own any of the characters. Otherwise, I'd make sure history doesn't repeat itself.
A/N: Ah, those things we write in 20 minutes. I like them.
Once the name "Lily" slipped past her lips before she could stop it, and this young redheaded girl looked up at her in confusion and innocence, and she had to leave the room. She had to leave her class, something she's never done before, not even when her entire life seemed to be falling apart as You-Know-Who was killing the entire world. She was always stoic, someone for the students to respect and admire, someone who would never show any weakness whatsoever. But calling a girl by the wrong name can cause her to break down.
It's not the mistake that hurts her; no, that's an easy mistake to make. She's a pretty, talented, lively young girl, a redheaded genius who's falling in love with a black-haired boy who is even more intuitively talented than she is. It's a good story; they should be friends, they should be lovers, they should grow old together. But she's heard it before, and she's afraid she knows the ending already.
Twenty years ago, a beautiful redhead whom she respected named Lily fell in love with a brilliant and irresponsible hero named James, and they fought together. They fought each other, certainly, but they also fought together, and it seemed they could never die. They came close, so many, many times, but they always came out alive, and she began to believe they were touched by something. She'd always seen magic as a tool, a fantastic tool but a tool nonetheless, but with these two it was something more. For these two, old-blood and Muggle-born, magic was life and love and mystery, and as long as there was magic they would survive. And then they had a son, and he looked like James but smiled like Lily, and perhaps they gave him their magic, because suddenly they were mortal. They had to go into hiding, and they died, were tragically killed, a century before their time. But their son lived on.
And now, another beautiful redhead whom she respects is falling in love with a brilliant and angry hero, and she's terrified for them. She is prepared for this war; she doesn't want it, but she's seen it before, and even if she doesn't survive she's prepared to fight until the very last minute. But if it were possible, she would hide these two away, lock them up with herself as Secret-Keeper, because she is prepared to die before giving them up. She wants them to live, to experience magic as life and love and mystery, to have the fantastic life that his parents deserved. But because they are exactly the same, she knows they will fight. They will fight each other, but more importantly, they will fight together. He'll try not to let her, as his father did, but she knows this story and they will fight together. It's a beautiful story, and they will be heroes forever.
But she'd rather they were alive forever.
She sees Harry and Ginny in the corridors, laughing and talking, friends who just happen to be in love. With her, he forgets that he carries the weight of the world, a weight that his father did not carry until he was old enough to choose it for himself. Perhaps that is what will make the difference: James chose this fate himself, but Harry has been carrying it his entire life. Perhaps everything that has happened to him has led him to this very moment, the cruelty of his childhood has strengthened him to be able to carry this burden in a way no one else could. Perhaps he is simply his father's son, and he carries the living magic of both his parents, and that will be enough to carry him through this battle. Perhaps she just wants to think so; after all, she finds herself believing something that is almost akin to Divination, an art which she has always despised.
But she wants to have hope. Harry and Ginny are not Lily and James; it's easy, very easy, to forget, but they are different. They will fight, yes, and theirs will be a very hard life, hard in the way most people cannot comprehend. But they can live through this; they have very strong friends and family, strong with the kind of strength that will not betray. She cannot doubt any of them, where she found it all too easy to doubt the friends that surrounded James and Lily. Those were breakable; these are not. She trusts Hermione and Ron, so like Remus and Sirius and yet so different. Hermione is as bookish as Remus, but she is not hated by all the Wizarding world, and she will protect Harry with her life (as long as Harry lets her). Ron is as angrily impulsive as Sirius, but he is the kind of loyal that will drive him mad before he can betray his friends, and Ginny is his sister. And the Weasleys and the Order will be familial walls for both of them, because Harry might as well already be a Weasley. And there is strength in this generation, strength that only comes from having been born in wartime and coming of age in another.
He may be James reincarnate, and she may be Lily reincarnate, but that doesn't mean the story has to end the same way. Perhaps (and she can hardly believe she's admitting this even to herself) they are here to set the story straight, to end it the way it should have ended. They can win this war. So she will teach them, and guide them, and protect them with everything she has. They will win this war.
History repeats itself, but she has hope. Without hope, all is lost. And these two know this best of all.