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Like a vampire, Vlad has to be invited into a dwelling or he cannot enter. Whether invited as himself or while overshadowing someone, he will be welcome to enter anytime until explicitly told, to his face, that he is no longer welcome by someone who lives in/has a claim to the dwelling, or regardless of his knowledge if the owner of the dwelling themself revokes his welcome. He won’t be compelled to leave if currently in the dwelling, but will not be able to enter again after leaving unless re-invited.
Danny constantly tells Vlad he is not welcome, but since Jack keeps inviting/welcoming him right back into their home, it does practically squat.