Once, in the middle of a school night before they'd even gone to Hogwarts, Lily was in Severus' bedroom with tears running down his face, barely holding her sobs down low enough not to wake his parents. She hadn't even known where he lived before that night, but something told her exactly what she needed to know to get to her best friend. He awoke with a start when she tumbled through his tiny window, stared at the broken-seeming redhead with his open switch still in one hand, then dropped it and scrabbled towards her.
"O-Oh!" She tried to be as quiet as possible. "Oh, Sev I just- just had the m-most terrifying dream ever!" Lily gasped and hugged him. "I-I don't kn-know why but it seemed so real, I nearly scr-scre-screamed!" Her tears soaked into his dingy nightshirt and her fingers didn't notice how sharp his ribs felt—she'd never been this close to him. "There was a man with a face like a snake, and you were there too, and the hateful snake said you were his, like a crony or a chess-piece to use and to lose, and you didn't say anything at all, you were so scary, nothing like you are now, and- and—" Her voice fading in and out of Power, Lily just broke down into heavier sobs, muffling them in his skinny chest.
"Shhh." It never even appeared in his mind that he was trying to quiet her down. "It's alright, it's just a dream, shhh Lily…" It sincerely pained him to see her hurting like this. The little boy from Spinner's End patted her awkwardly on the back, hugging back with his other arm. "Just a dream..."
"But- But Sev, it scared me." The redhead, older than him by about a month but emotionally far younger sobbed. "What if it's a vision like when I—and— it's the thing I like most about you Sev!" The streetlight barely illuminated her face, but she looked him earnestly in the eye. "You're your own person, nothing nobody says or does can make you do anything that you wouldn't do anyways! Without that, you wouldn't be mySev."
He shivered.
"Promise me Sev." Lily coiled her arms as tight as she could without fear of hurting him, shaking him when he didn't say anything. "Promise even when you're all grown up, you're your own man. Promise me Sev." Green eyes still terrified from what may have only have been a dream, tear-tracks shining in the poor light.
"I promise." Sev, as long as she'd known him, had moments of complete solemnity. But the way his faced shifted into something much more determined than just serious. "I promise I'll always be my own person, no one else's, as long as you're my friend."
"The-Then I promise that we'll be friends forever." Lily smiled, for the first time that night.
"You—I don't want you to be my friend 'cause you promised." Sev shook his head, still solemn. "All the time we're friends, I want you to want to be my friend. You don't want to, just say so, 'kay?"
"Shut up Sev." She wacked the back of his head. "I'll always wanna be your friend."