Dante and Isabella aren't the kind of vampire in old myths. I tried my best to make the vampires in the RP a hybrid of old myth and modern ideas of what a vampire is. Their weaknesses are fire, holy symbols(not just a cross but any holy item), sunlight to a degree, sanctified ground, and holy water. So in a way water is a weakness but only if holy water so the lake wouldn't harm them but Kyle could if he were to bless his water.