In a heck of a lot of vampire fiction there is a war theme between vampires/humans/werewolves/etc.
I’ve never figured out why humanity or individual nations don’t just offer a vampire amnesty, people will donate blood for you to live on AS long as you don’t kill.
As for 2 the vamps are out killing already, and seem to have done alright for most of human history. Plus donated blood could cut down on the number of vamps er “born” in the wild.
What was that show with the vampire detective? Not Angel, the other one… no, not Forever Knight, the other other one…Moonlight! That was it. He bought bagged donated blood - I think maybe it was even expired as related to transfusing it, just to drive home that he was Totally Not Evil, He Just Has Good Hair. And in a meta twist, there was a blood drive in reality organized to try to “save the show” when it was (not) canceled.
There was a vampire “brothel” in Buffy, where one fairly major character Riley went to let vamps feed on him because…um…because his heart was really black and wounded, or something (it didn’t make a whole lot of sense to me, honestly.) Sort of the inverse, really. I don’t think he was doing it out of the kindness of his heart, but the vampires did get a meal out of the deal without killing anyone.
Jim Jarmusch’s recent Only Lovers Left Alive featured Tilda Swinton & Tom Hiddleston as two elegant, cultured vampires who preferred to feed off blood obtained legally, if discreetly. Medically screened, of course, because you can’t be too careful nowadays.
Kim Newman’s Anno Dracula series is a pastiche of all vampire literature & folklore (& other literature & history). It’s an alternate past that began when Van Helsing failed, allowing The Count to turn & marry Queen Victoria. Many undead managed to live with a minimum of fuss–but others tended to get out of hand…
It is a valid approach. Either the Friendly Neighbourhood Vampire or the Vampire Overlord could act in this manner, drinking donated blood or from groupies rather than operating covertly or demanding more onerous tribute.
Can’t we just kill all the vampires? That would be easier. Go all “Picard at Borg” on them and infect a person with some vampire-deadly pathogen than can be spread like rat poison to the vampire hive.
Or nuke 'em from orbit. Whatever.
What IS it with vampire fascination? Goddamned (literally) blood suckers! At least John Carpenter’s Vampires had the right idea. High tech hit teams hunting them with the Vatican’s blessing (again, literally).