His first thought was that Nettie might well have been here, before he realized that he was being utterly stupid and that it didn't sound like her at all. Izzy gripped the fire poker tightly and ran after John, ready to strike anything that came within spitting distance.
Izzy saw the woman as soon as John did and surreptitiously moved closer to him, keeping perhaps a closer eye on the vampire than his surroundings. If the woman were human, then she might be in more danger than whoever or whatever had made the scream. When he saw John raise the poker, he instinctively grabbed his arm and made to pull it down with perhaps more force than he should have applied if he wanted to come off as human.
"I...will deal with this, no need for you to put yourself in danger, sir," he said with strained politeness before heading further into the room, not letting go of the vampire.