"Well, we didn't know which house you were in," Lily murmured. "Your mum thought you'd be a 'claw, I think." She wondered if Ginny would be disappointed, but she didn't think she would be. Not outwardly, at any rate. Lily herself harbored no prejudice against the house itself, though several of its members had earned her displeasure while she was in school. It was a house, the same as the others. She disliked Death Eaters and Pureblood elitists, not Slytherins.
"Though I'm sure ..." Actually, she was sure of nothing when it came to Severus. Things were still so shaky between them. "Well, I suppose I'll leave that up to you. He checks the boards so I'm sure if you addressed a note to him, he'd see it." He might not respond to it, but Lily was sure he'd see it.
"Come on then," she encouraged gently. "We'll go see who's home and introduce you around."