Severus flung open the cabinet upon arrival to Dumbledore's office, snatched the pensieve and slammed it onto Dumbledore's desk. Carefully, he wiped his eye to clear a tear and then tipped the droplet of silvery-blue liquid into the basin.  As the pensieve swirled, he looked up, at you.

"Put your face in it."

"But Severus,"

"NOW! You must know! You must know all of it! If he is back, he will come for me and in return come for you. If you do not know every little thing, he will use you to get to me. You must know all of it and then hide it away. Dumbledore said your occlumency was almost unrivaled. Look, so you will know why I have such complex feelings for the boy."

Putting your head in, you begin in a quiet neighborhood. All you can hear is a baby crying when you see a man. It is Severus, with his chest rising and falling. He looks stricken... concerned. Before you can follow him in, however, you are whisked to another memory. "Lily..." Severus' much younger voice says her name as she stares at Severus' palm. A flower is there, floating. Then, another girl enters.

"Lily!  Come out of there!  Now!" Lily shows the girl the new trick. "We're going home." She takes Lily's arm, swatting the flower out of it and turns. Then stops. Young Severus is sitting beneath a tree, watching them.  Without a word, he opens his hand and a leaf flutters from his palm like a butterfly, circling Lily once, then drifting up and away.  Lily smiles, charmed. The other girl eyes Severus fearfully, then pulls Lily away. He watches them go.  As Lily glances back, you are whisked back to the first memory.

Snape moves through a dark garden, his face like stone.  He eyes the door ahead, hanging from its hinges.  He peers up to the window above.  The baby's cry rises again and Severus' eyes glitter with tears.  He moves on and disappears inside, pulling you into another memory.

Lily and Severus, a boy covered in bruises and mismatched clothes, lay together, staring up at the sky. "She's jealous.  Because she's ordinary and you're special." Severus' young voice speaks. You like the sound of it.

"That's mean." Lily protests.

"It's true.  You know so yourself." Severus turns his head and notes the frown knitted across Lily's brow. You supposed he had always had problems communicating.  He peers back up, staring hard at the tree limb above.  The leaves begin to tremble, then burst free, fluttering like a cloud of butterflies.  Lily watches impassively and then, slowly, smiles, shifting her gaze to another branch.  Seconds later, those leaves burst free and the two fluttering veils pass back and forth high overhead, merging briefly, then separating, again and again.  Lily laughs and you are transported yet again.

Severus peers out the window, watching Lily and the other girl, her sister you assume, on the platform arguing.  Finally, Lily turns, dashing for the train in tears. Severus straightens up, running the flat of his hand over his lank hair-- he wants to look good for her.  Moments later, Lily comes up the aisle, eyes stinging.  She stops, seeing him.  They stare at one another and then, finally, she steps inside the compartment, and sits down.  The boy reaches over, pulls down the blind, which is exactly what you think he will do. He has always been sweet and caring.

There's only a short time skip and you emerge into a sorting ceremony.  As the younger Minerva McGonagall lowers the hat over Lily's brow, a boy you recognized as James Potter watches intently, waiting.  Finally, Minerva speaks and all those around James cheer.  He merely smiles, watching Lily approach.  He gives Sirius a nudge, to move over, making a space for Lily. As she takes her seat, she glances across the hall to Severus, who was obviously sorted into Slytherin, who watches impassively as James reaches out his hand to introduce himself to Lily.