Lillith laughed a bit at the idea of Isaac being called a boy. He looked like an adult to her, and as far as she could tell, he was an ancient supernatural like Vlad.
"The woman is a prisoner, mother of my Uncle's adopted daughter. The child is my Uncle's adopted daughter, but don't tell her she's adopted. That 'boy' is Isaac, who will hopefully become your boss, and not Ivan. He's Vlad's loyal subordinate, and is better than Ivan, in my point of view. He doesn't serve under Ivan, and he's not an asshole."
When Lillith was inside, she asked a servant if Vlad's business was done and where she could find him. The servant did not know, unfortunately. So Lillith simply headed off to where Vlad had last been seen.