Most people kill them, and walk on.
But I noticed this today, both Berenike Knights and Balder Knights never made it the Anor Londo, all of them hollowing at Sen's Fortress.
So, why are these knights there?
And then, on to the next question.
Why do they attack you?
The Firekeeper has a reason to attack you, she is a known Blade of the Darkmoon. But these knights show no ties to the Blades of the Darkmoon. They don't use the miracle, they aren't spirits of vengeance, they aren't using anything related to the Darkmoons. So why do they attack?