There isn't much any sim can do with/to total strangers. I'm pretty sure that at least one type of introduction or another is needed before most social commands become available. And then, in other contexts, sometimes the celebrity system puts up a further barrier and one has to "impress" the other sim in order to proceed in case that's relevant.
As for the two vamp actions noted, they possibly need a higher relationship score than what they are starting out with on those other sims before the commands become available.
