He’s not a thrall; he is a civic-minded and altruistic individual who makes frequent blood donations of his own free will. Ask him yourself. I trust you will forgive me, but I have much work to do in private this evening. You will, I hope, find all things as you wish.
Those of us with hemochromatosis might be perfectly willing to come to an arrangement without all that messy hypnosis.
IIRC there was a move (a comedy) where Dracula was finally driven out of Romania by Communist officials after they confiscated his castle & estate.
The main character in The Age of Adaline had to move and start over with a new identity every decade or so; she even showed her started the process at a bank added a new “assistant” to her accounts. Aside from her daughter the only friendship she was able to keep up over the decades was with a blind woman. And also her own daughter; who was of course in on her secret and up apparently pretending to be her mother’s grandmother.
I read a comic called Vampire Life Sucks (or maybe it was Bites) a few years back where this issue was considered.
In the comic it’s really hard to sustain a vampire identity. The protagonist had a minimum wage night job with a crappy boss, and rented a room from a human who obviously knew what he was. (Said protagonist was a really nice guy by vampire standards. As he never drank human blood, he never developed powers like domination.)
Vampires in human lore exist outside the southeast European model dramatized and popularized by Stoker (following Polidari and Le Fanu).
European vamps range from bestial revenants to suave aristos. Elsewhere they’re mostly demons. Effectively immortal vamps may drain any sort of life-substance: energy, blood, genital juices, or some odd secretion if an author wants to get kinky. Vamps subsisting on toe-jam FTW!
One can play with the Euro tradition. I recall a cartoon of a victim whipping out a cross; the vamp says, “Oy veh! Are YOU in trouble!” Another trick within the tradition: vamps may be effectively immortal but are mostly not aristos of high intellect but arrogant punks with the instincts (and brains) of skunks and porcupines. They’re killed by clumsiness, not daylight. The lucky ones stay rich across a few centuries, maybe exploited by the family of their human aides.
Or choose or invent another tradition, maybe with a kingdom where royals and aristos are all vamps feeding on captives for centuries. Each succeeds themself. Queen Larynga VIII looks an awful lot like her “predecessors”, as do her court with theirs. Royals and nobles contend for power in entertaining ways. Will Magic Heroes overthrow the status quo without going vamp themselves? Stay tuned for the next thrilling episode!