You are approaching the Albedo Cave, where the main alchemist camp was located in Mondstadt.

when you entered the cave, you saw Dorian standing near the alchemist's laboratory table, as if he was looking for something

as soon as Dorian noticed you, he looked at you with a stern look, pulling his sword out of its scabbard

Dorian: Who are you?! Albedo's assistant?? If so, I'll kill you!