So I was thinking, and I couldn't come up with a reason why Snape would want to stop teaching something he's so good at and take the cursed Defense position. So I decided I would find a good reason. Mildly Depressing. Please R/R!
April 14, 1976
It was the first clement day since winter, and Severus was contently reading by the lake. Beside him, Lily Evans was sitting with a Transfigurations essay on her lap; but she wasn't really working on it, Severus noted. Instead, her beautiful emerald eyes seemed focused on Hogwarts itself. They sat there, her looking at the castle and him looking at her, for a long time. Eventually, Lily broke the silence with a blithe sigh.
"Sometimes I wish we could just stay here forever, you know?"
Severus replied blandly, "Shame that would mean failing indefinitely, isn't it?"
Lily just smiled at her friends snark. "Not necessarily. We could be professors. Then we would get to live here all year round. Wouldn't that be great, Sev? We could still be neighbors, even when we're thirty and married."
Lily never noticed the way Severus smiled, actually smiled, at married. But she couldn't miss his sarcastic response of "I doubt Dumbledore would hire us both as Potions professors."
"Okay then," Lily chirped, "I'll be the Potions professor. And you can teach Defense Against the Dark Arts, you can do that sort of stuff." Severus braced himself for a comment about his stupid evil pureblood friends, but the comment never came. Lily looked over at him "How does that sound?"
Better than having James Potter turned into a toad. "That sounds wonderful." For the second time that day, Severus smiled. "All the students will love you, they'll probably come crying to you when they get terrified of me."
"I hope you won't be scaring our future kids, Sev. " Lily reprimanded. And even though he knew she meant students, something inside Severus purred when Lily said our future kids.
"I made a first year I was tutoring bawl last week."
"Well, the fact that you were tutoring him willingly shows potential," Lily jokingly consoled, "We can work on your teaching style."
And in that moment, Severus could see that future so clearly, he wondered if maybe he should have taken Divination. He could see Lily, older but just as beautiful, teaching him to have patience with annoying students. He could see them laughing at the Head Table, quietly making fun of the other teachers. He could see them at the Sorting ceremony, cheering every time a student got sorted into their former houses. And he could see them, sitting side by side, drinking a cup of tea after a long day, talking about this and that.
It was a future far better than he had ever imagined for himself, far better than the one he had planned. But in that moment, it seemed possible for him to live out the rest of his life at the side of the love of his life.
"Promise?"
Severus was shocked out of his train of thoughts. He turned to see Lily looking up at him with her big, vibrant green eyes.
"Do you promise it'll happen? That you'll do everything you can to make sure it happens someday, with you teaching Defense and me teaching Potions?"
It was the easiest question Severus had ever had to answer "Yes."
Lily giggled hysterically, and enveloped Severus in a hug. And while it was kind of awkward for him, Severus admitted to himself that it was really nice too, having her hug him. "Best friends forever, Sev. We'll always be together," was whispered in his ear, and Severus, for the first time he could remember, smiled for the third time in a single day.
A week later, Severus ruined their friendship forever. Six months later, Lily was dating Potter, and within the year, they were married. Severus Snape realize that Lily would not uphold her promise. But, even ten, fifteen years later, Severus would keep trying for the Defense position; even though he knew he was better at Potions, and a horrible teacher altogether. No one had ever taught him patience.
He knew, logically, that Lily Evans was dead, and never going to come back. That he had had a part in killing her. But a small part of Severus Snape, the same part of him that demanded he protect Lily's son (a part that in a lesser man could be called a heart), desperately needed to keep his promise.
He felt, in that part of himself, that if he could only keep his promise, everything would turn out. Every horrible thing he had ever said and done, all the horrible mistakes he had made, would be reversed, and he would have Lily back.
His entire life, Severus' deepest desire was to be married to Lily Evans. But when he looked into the Mirror of Erised,he saw himself with Lily in a happier, better decorated version of the Potions professor's rooms, enjoying a cup of tea and talking. Together. Always.