It didn't take Sirius too long to catch up with her, since he'd been just about ready to go anyway. He thought it was too bad Remus had declined to come along, but he wasn't too surprised; it was getting close to the moon, after all.
"Were you trying to ditch me, Evans?" He asked as he fell into step beside her, slinging his arm around her shoulder. He knew he had been a bit hover-like the first week or so, but all things considered, he didn't think his behavior was out of line. Maybe he wouldn't even stay long at the bar, but he hadn't decided yet.
After all, there was something a little off-putting about Lily going out dancing on her own. Mostly because when he went out like that, it was to look for someone to spend the night with. While he didn't think that was Lily's aim, other guys at the club wouldn't know that and it was obviously his duty to James to protect Lily from any unwanted advances.