A/N This is a rewrite, at the request of ilovelobsters...I've only changed the last paragraph, though, nothing drastic.
Sometimes, you just know these things. It doesn't take an orchestral choir singing or trumpets sounding or a messenger announcing it. Love isn't all hearts and flowers. Sometimes it's as subtle as a butterfly's breath on the breeze. Sometimes, love isn't ostentacious or beautiful. Sometimes, love is just love. And when it happens, you don't need to be told. You just know.
The same way he knew it now. He knew it was love that made his heart skip a beat when he saw her walking through the corridors, beautiful hair tossed behind her halfway down her back. He knew it was love that stole his breath when he looked over the opposite side of the lake to see her sitting there, laughing with her friends. He knew it was love that released butterflies into his stomach when he heard the sound of her voice on the breeze. He'd always known it. He loved her.
He had lost count of the times he'd made his feelings known, the times he'd reminded her of her beauty, laughed loudly in appreciation of a joke she'd made. He couldn't recall the number of occasions on which he had gently brushed the thick red hair back from her face to reveal those green eyes, shining at him like liquid jade and full of the goodness he knew ran through her. He didn't remember how many times he'd felt nervous or been worried, only to see her smile and feel new spirit revived in him.
But when it came to remembering his first realisation of his feelings for her, his memory was crystal clear. Their very first day at Hogwarts, when he'd been feeling anxious and the entire first year was being herded from one place to another. That first day it seemed to him that they were always being shepherded around, and, being who he was, had quickly tired of being told what to do, where to go. His natural curiosity taking over, he had turned, intending to sneak away and explore. He'd walked straight into her, knocking her to the ground. Her face had been obscured by that thick curtain of red hair and he'd extended his hand to help her, expecting her to be hurt.
Not Lily Evans. She'd come up smiling and with that one action had secured a place in his heart forever, without even realising it. He had known then that this girl was special, and even if he'd been too young to give a name to the feelings that he'd suddenly borne, he knew what they meant. And now six years had passed and he'd seen her grown more beautiful, more lovely. He'd seen her innate kindness, her compassion, her intelligence. He'd also seen her cold fury, her skill at hexes and, equally, at counter-hexes. Lily had always possessed a forgiving nature.
She could even be nice to Snape - this alone more than anything else proved to him the size of her heart, because all she ever received from Snape were veiled threats and whispered animosity. Not that he allowed him to get away with it - no one insulted Lily Evans when he was present. Nobody. And yet still she saw him as nothing more than a nuisance, him and his friends. She refused to have anything to do with him, with any of them, and he couldn't understand it. Couldn't she see the love he bore her? Was she so blind to his feelings for her?
At night he occasionally prowled the dormitory, dark thoughts whipping about his troubled mind. How could he show her he was different, persuade her he was a good person, when all she ever saw was him at his worst? He dreamed of her, her tawny hair, her perfect smile, the light freckles that dusted her nose. He knew now that he had a serious problem on his hands. He had loved Lily Evans for many years now.
The trouble was, he wasn't the only one. He had spent long, torturous hours lying sprawled on his bed, tossing and turning, air around him thick with all the what-ifs and the if-onlys, so many that he was denied sleep. He lost himself in glorious visions of himself sweeping her off her feet, offering her everything she could possibly want, and Lily not only being flattered, but positively euphoric. But in the crashing silence that always surrounded him during his late-night ponderings, he would inevitably be drawn to the same, inalterable conclusion. She would be better off without him. It was simply too dangerous. The call of the Dark side was too strong, and he knew that one day he would be dragged under it, perhaps not willingly, but it would be his doom nevertheless. And he would not allow her to be taken down with him.
His competitor for Lily's love, on the other hand, told a different story. His rival could offer her everything he himself could, but with the second boy came the irresistable aroma of safety. Security. Oh, he didn't kid himself that she would be completely safe. No one could guarantee anything like that in these times they were living in. But if he allowed her to choose, he knew who the better choice for her would be. And so, leaning out of the dormitory window, the chill night-air cool on his face, he made up his mind.
James Potter would have the girl whose love he so desperately sought. Lily Evans would be saved. And Sirius, whose family were so intwined with the Dark Arts, would sit on the sidelines, and watch over them both. It was for the best, after all.
At least, that's what he told himself.