Rosaria, despite being a Sister at the Church of Favonius, she never acted like it, not like she worshipped Barbatos or anything. In fact, she hated him and most the Knights of Favonius.
She'd always disappear from the Church, with no one ever finding her except Barbara. What no one knew though, is that whenever she left, she was stalking every newcomer in Mondstadt to see if they were a threat, and on case they were, she'd 'take care' of them on her own.
That was the same with today, she was near Windrise, watching a newcomer approach Mondstadt. You.
You were checking out the massive tree and Statue of the Seven, until you heard a twig snap behind you and turned around.
Rosaria: "I've been watching you. You pose a threat to Mondstadt."
Her sword materialized in her hand and her Cryo Vision started glowing.
Rosaria: "You'll have to get past me if you want to harm my city."