Lily Evans had a secret, too, though Snape would never learn of it.

It was winter 1979 when he last spoke to her. The air had that smell that only the first snow can bring, and to the end it would stay linked to the memory of touching her hand.

They walked side by side, and Severus set each step carefully, gently, as if worried that any sudden movement might break the fragile illusion. He held her hand in his, and could feel the ring around her finger, its magic rebelling against his touch, growing painfully hot.
Yet she let him, Lily Evans. Evans. Still there was hope, still the story could...

Lily laughed softly and sadly, a short sound that could almost be mistaken for a cough. Both stopped and turned to each other, but did not dare meeting the other's gaze.
The snow muffled the sounds in the pasture, and it was as if they were the only people in the world. Snape's breath came in shallow, shaky puffs and condensed in the air between them.

Couldn't it be forever, he pleaded to himself, please, let this moment stay forever, no matter what the price, I swear I'm willing to pay it.

"Why won't you understand?" asked Lily sadly, the moment shattering as she withdrew her hand.

Severus took a rattling, deep breath, and his chest pressed against the bottle in his coat pocket. Just a small vial, a finger's width in diameter and three finger's width filled with a transparent, viscous liquid.

An extract of Amanita Mortium, brewed with the same precision and craftsmanship with which Snape made all his potions.
The mushroom was a relative of the Amanita Phalloides, the Death Cap fungus, feared among Muggles, and surpassed its cousin in potency.
The liquid would taste sweet, rob him of his magic, and then, eventually, his life.

"I *can't* understand it," Severus finally groaned, "you said you, no, we, we belong -"
"- it doesn't matter what I said," Lily interrupted him, "please understand this. The past is the past, and now is now. We've all made our choices, and I'm happy with him."

Heat rose in Snape's chest, crept up his neck, filled his head, and burned in his eyes.
"If I had known... if you had told me... that you..."
He didn't finish the sentence and looked at her pleadingly.

She returned his gaze with her bright green eyes. There was a crooked smile on her face, filled with pain and affection.
"Severus. Severus."
He felt like the ground was pulled away beneath him, and he was falling. He wanted to fight, needed to fight, but he knew it was over. It was done, none of his mistakes could ever be undone.

"Lily, please, I promise you, I will change. I will -"
She shook her head gently.
"No, Severus. It wasn't meant to be. You and I just don't belong together."

She reached for his arm in a gesture of comfort, but he backed away and raised his hands defensively.
"Don't touch me. Please, don't touch me. If you touch me, I will die."
He could no longer suppress it, tears forming in the corners of his eyes.

Lily laughed again, her soft, sad laugh. There was no mockery in it.
Severus, oh Severus. Always so dramatic, so melancholic, so... intense. More intense than reality, as if only the moments with him were real, she was only really alive around him.
He attracted her, still, and he destroyed her, still.

She knew what she had to do. Some secrets could never be spoken.

"Severus, you're just not the right man for me."
He tried to respond, but she remained strong in her resolve.
"No, and you never will be. You and I don't belong together. Please, stay safe."

It must have been hours that he knelt in the snow, his fingers, long since numb from the cold, closed around the vial of clear liquid. Her voice had long since faded from his memory, only white noise left in his ears. It was the last time he cried.

Lily Evans was gone, and had taken her secret with her. She knew that sometimes dreams had to give way to reality. She knew she had to make a choice, and she knew the right one.
She chose a pragmatic, realistic, and stable love that she could build a life on.

Her other love, her first, in all its frightening depth, she left in the snow that day. She knew she would never feel anything of such intensity again.
That was her secret.