I found this:

Perennia Draconis wakes up at around 7, goes out and works on her crops. She then stops at around five and reads a book for most of the day. She then goes to sleep without eating.

Mathias Draconis works at Umbacano. I first expected him to have dinner in the Umbacano dining hall, but actually nobody does. I then followed him more closely and he has dinner at the Bloated Float. I cleaned out the place and dropped a poisoned apple in his inventory.

Caelia Draconis doesn't eat either. She is either asleep in the barracks on randomly patrols Leyawiin. In the morning she sits in the upper room at the Three Sisters' Lodge, like a plum without doing anything.

Andreas is either asleep or standing behind the counter. He does nothing else.

Sybylla Draconis was a bit harder to stalk, and unsurprisingly she actually doesnt do anything. She's not a vampire from the looks of her (might be a vampire at early stages?) but she doesnt even sleep.