Vlad thought it was interesting, the way Maddie's pupils widened when she looked at his invisible form. Even in full light, she seemed to have complete control over them, and it made him wonder if he was truly invisible. Perhaps some small glimmer of his form remained enough to create a vague silhouette, or it might have been that she could see his ghostly aura.
And he knew she could see him. He would hold an invisible hand over her and wiggle his fingers as he did when he normally played. She would pounce, reaching out with retracted claws to try and catch him. He would levitate off the floor and silently leave the room, Maddie following him, especially if he happened to go in the direction of the kitchen.
For the longest time, he wondered if she could see all ghosts, despite their state of visibility. Would her sharp green eyes pick up on any spirit that dared enter his worldly lair?
(There were times he was tempted to leave his Portal open in an attempt to lure in some intruder, but knew the satisfaction of his curiosity would be far less rewarding than the blow to his reputation should he allow the other ghost to escape.)
Or would she look only at him, stretching up the length of the wall to rub her head against a knee that wasn't truly there?