Katherine is definitely interested. She grins gleefully as Stefan compels and feeds on the Extra, her grip on the railing tightening and nostrils flaring slightly at the scent of the blood in the air. She's pushed herself off of the railing and is standing in front of Stefan only seconds after he turns around to face her, invading his personal space.

"Mm, this look suits you so well," she murmurs appreciatively, wiping at a smear of blood on the corner of his mouth with her fingertip and bringing it to her own lips, licking it clean despite the awful taste. "You should wear it more often."

In truth, she's rather disappointed she didn't get to see Stefan indulge this side of him after he'd been turned, remembering the conversation they'd had during the zombie invasion in which he'd alluded to having done just that.