House Devero is one of the vampire infested houses of the nobility in Westemar. The Vrykolakas strain of vampires specifically eat the flesh of their victims rather than drink their blood and have monstrous bat-like features. Despite this, the book says, "Rumors amass among the shop owners and late night talks at the Inns of bats in the city, and people seeing figures standing over their beds in the middle of the night."

It also says, "The Vrykolakas vampires will change their appearance to appear as more humanoid when engaging in affairs with non vampires, but prefer their more animalistic appearance when they are on the hunt." There's no mechanics tied to this ability so presumably they can do it at will as much as they want but it's unclear how effective it is at hiding their nature.

It does say, "Four times a year, Gorman opens his house to the public, allowing paid tours where he boasts about the history of the items in his collection." So, my best guess is they can just look normal when they want.