@shelbeast Sorry, i am slow to reply.
If it is with NPCs on a MU* then any RP is to an empty room most of the time. I could see saying that a vampire cultivates a type of relationship with a given target, and you could pair the feeding value of that investment in time to greater security risks, as that target is something that has a stronger link to the vampire in terms of time spent together, and if deprived your blod throughput definitely takes a hit.
That could track the style of feeding of a vampire, but it doesn't provide the story. It would take a neighborhood/town/city generator to track the importance and risk associated with a given individual, and no one builds any simulator that complex for RP.