A serious fantasy drama about orphan kids? Also has a invisible lizard.

There are a brother and a sister who live with their uncle/guardian who has snakes/maybe other animals too in his house. Some person kills the uncle/guardian. They move to some village. There they live in a house by a sea shore and the house also get destroyed.This is the best i can remember.Also the killer chases the kids but he fails to kill them. The town is kinda weird everyone stares at them. They purchase some things in the marketplace.