[Smiling a little more at that look from around his cigarette. He has missed this, honestly.]

Once you become a vampire, you slowly start to lose touch with everything that made you human. You don't actually feel emotions anymore. You can't eat the food or drink the things that you used to enjoy without effort. You can't walk under the light of the sun without help.

[Then, softly:]

You're effectively a dead man walking, with nothing but memories of everything that made you what you were slipping a bit more every time you give into the urges that make you a vampire.