Lily had been ignoring him. She'd left him and his aspiring Death Eater friends alone. "It's them or me," she'd said. They were hardly friends, merely accomplices in their research and united only by their shared goal but he needed them. When Lily walked away from him for the last time, he felt the tangible, crucifying grip of heartbreak and regret overtake him. There was only one thing he could do: brew a potion.

Four weeks and one day was precisely the length of time Severus Snape spent away from Lily before he finally found his salvation. It took many experiments but he was finally ready to make it. Acquiring the ingredients would be impossible alone, so he convinced Avery that the potion was something of a weapon he could use to aid the Dark Lord. With sickening glee, Avery helped Snape steal the ingredients by creating a distraction.

A cry of "Levicorpus!" sounded as Avery targeted a Mudblood. As crowds of people began to gather, Snape slipped away and headed towards the room in which Potions was taught. The last class finished hours ago, so it would be empty. Slowly, wand raised by instinct, he pushed the door ajar with his free hand.

Bright green eyes looked up at him, wide with shock. A brilliant gold liquid was simmering in the cauldron over which she was stooped.

"Severus," she said quietly, unafraid. "I think you should lower your wand."

He hadn't realised his wand was pointed at her. He tucked it away and stalked over to the furthest reagents cabinet. It was too risky to steal the rare ingredient he needed from the professor's desk. He took a bezoar for his trouble but lingered, hoping - almost praying - that Lily would beg him to stop, to come back to her. Of all people, he thought Lily the only one capable of caring about him.

Alas, she said nothing. He had driven himself so far into his obsessions that even Lily refused his companionship. She'd made him choose between her friendship – nothing more – and his accomplices.

Had he been in Gryffindor, would she have ignored his dark pursuits because of his inherent bravery and courage? Would she have seen him in the same light as he saw her?

Could she have loved him?

Perhaps. He would never know.

And so it was with great pain and anguish that Severus Snape approached Lily Evans at her cauldron, struggling fiercely to hide his emotion.

He took a moment to compose himself.

"Lily," he whispered. If he spoke any louder his voice might betray his suffering. She met his eyes, staring with those beautiful, intelligent green eyes into his own dull ones, into the depths of his soul. He would've given anything to stay in that moment forever, utterly captivated by her.

Then, she smiled.

"It's alright, Sev." She spoke softly, her voice smooth as silk.

He wondered how the world could be so cruel. Of the hundreds of students Hogwarts saw every year, only one had been blessed with every good trait of humankind. She was a creature of love and light, of wisdom and kindness. He was capable of love, that much was true, but he knew it was not his destiny to love anyone but Lily. Her purity and kind heart should never be tainted by his corruption and fascination with darkness. He'd never forgive himself.

His vision began to blur and only when he felt something drip from his chin did he realise he was crying.

Lily smiled again. She approached him, producing a delicate white handkerchief from her robes. It hit him, finally, that this was goodbye. Even in her repulsion to his corrupt obsessions she found it in her heart to gently dab at his tears, caressing his face.

"It's alright, Sev," she repeated.

"I-I'm so sorry... I-" but she had cut him off. He felt faint.

Lily was kissing him.

Her lips were soft and warm on his, kindling within him a feeling he had suppressed for exactly four weeks and one day.

He kissed back, timidly at first but then he matched her gentle pressure.

Time stood still.

He closed his eyes, bathing in the warmth that is love, savouring the only time in his life Lily would be his.

She pulled away and he opened his eyes to see her cheeks flushed with colour.

"You still have time." Lily's eyes darted back and forth as if she were reading her thoughts from an invisible book. "You can reverse what you have done, forget the Dark Arts."

"I think... there is no way back," he whispered after too much time passed. "Do you believe in destiny?"

She nodded.

"There's no way out for me now. It's too late. The only foreseeable way forward is the Dark Arts."

"How can you possibly know that? Do you enjoy that we are no longer close?!"

"It has to be that way, Lily." He was trying to convince himself. He wanted nothing more than to hold her tightly and never let go, but he knew it would hurt her more than he could bear. He would be her silent guardian but nothing more.

She shook her head, eyes sparkling with tears.

"Severus..." she whispered.

He managed a smile that didn't quite reach his eyes.

"Goodbye Lily."

A number of years passed before Lily forced her way back into Severus' life. Without the drama of Hogwarts intensifying his emotions and clouding his judgement, he found solace in her friendship and learned to tolerate James Potter, though he never quite forgave himself for pushing her away.

The bittersweet memory of their last kiss and first goodbye haunted him until the moment he took his very last breath.