white avenger
white avenger
I'm assuming Buffy skipped town during dead man's party
Okay, I was assuming that she left after the Season 2 finale and never returned. That would leave the possibility of Giles finding her and their setting up shop somewhere not Sunnydale with Counsel approval and support. In that case, if Faith were, indeed, running to her sister Slayer for help, she would probably know Buffy's new location and head there, not to Sunnydale.
("How would Faith know Buffy's new location?" you ask. The same way that she knew that Buffy was in Sunnydale in the real story line.)
Two different possible scenarios.