Lily had been lost in her own thoughts and she didn't see the other redhead until they were very nearly on top of one another. Even as the girl spoke, an apology was on Lily's lips as well.
"I'm so sorry, I wasn't paying att-" Lily trailed off, laughing softly. Not knowing who the girl was, she felt none of the awkwardness of recognition. Instead, she offered her a slight smile, despite the mood she was in after that conversation with Sirius.
"There must be something in the water," she joked. "Hi, I'm Lily."