Does he know that he sounds jealous? That he has reason to be? It's an interesting concept to consider, but the evidence he's found thus far runs to the contrary. In some ways it's easy to liken Vanitas to a child- inexperienced with his own emotions, unable to name them and unfamiliar with the cause. The trouble with allowing that similarity to become a blanket assessment is that it minimizes and even eliminates his capacity for agency. Children learn because people are there to model, support, and sometimes teach- they see that their actions have consequences and develop empathy through experience. Vanitas has already passed these benchmarks, not through personal growth and development, but through cultivation. These beliefs and ideas, the way that he acts, these are not innate. These traits have been learned.

He takes up his fork like a weapon and just holds it for a long moment, before he starts stabbing at his eggs.

This is the first time he's mentioned 'Ventus.' Bruce recognizes that it's significant immediately even if he doesn't yet have the details to contextualize it. But with that recognition comes the awareness that this isn't the time or place to pursue it. Vanitas is terrifically hung over and quite possibly also still drunk. Bruce does not have qualms with taking advantage of a situation that presents itself to him, but he can also recognize when his gains will be outweighed by his losses. It's an easy decision to make.

Vanitas has been hurt and exploited in the time before he's come here.
Bruce doesn't want to be one more person to add to that list.

So instead he reaches across the countertop, with his mug still at his mouth. He looks Vanitas in the face as his fingers wrap around the neck of the liquor bottle and begin to lift it. He is, visibly, baiting him. "I suppose you're finished with this then."