Überwald League of Temperance
Times change, even in Überwald. What with advances in communications technology, interfering Witches and the rising influence of Ankh-Morpork, the populace is ever less willing to accept some of the old traditions, such as having the blood drained from their bodies by Vampires. Mobs of peasants and townspeople equipped with torches, pitchforks and sharp wooden stakes have become common around the dark castles of the undead, causing some reflection among thoughtful Vampires. Many of these have concluded that an alternative life style must be found before they are all staked, beheaded, burnt and consigned to running water. (Better communication has spread Vampire remedies, for one thing.)
To promote a healthier, safer modus vivendi, some of them formed the Überwald League of Temperance, a self-help group to encourage each other to abstain from human blood. The League operates as other organisations of the sort, even on Roundworld, offering emotional and practical support to withdrawing Vampires and proselytising among the rest. Lady Margolotta is an early member and a driving force in the movement. Lady Margolotta realised a long time ago that the craving for blood is still only an outward manifestation of something more fundamental still - the craving for power and control. If she can control her fellow vampires through the League, then that's a lot of power in her hands.
Members attend regular meetings and wear a black ribbon to show their affiliation and reassure their human neighbours. The League uses the motto "not one drop" and slogans like "live not in vein." The movement has spread to other regions like Borogravia and the Ankh-Morpork League of Temperance now tends to the needs of the many black-caped immigrants to the city, where people (and particularly the Commander of the Watch) are even less tolerant of the "old ways."
The only obvious downside of the movement is that recovering vampires are forced to shift their original obsession for blood into something else, often with varied results; Otto Chriek, for example, has become an Iconographer, despite the notable handicap of collapsing into dust whenever he uses a bright enough flash, and Maladict's new obsession with coffee leaves this particular vampire prone to shakes and potentially more likely to be overtaken by baser instinct if deprived of it.
Annotation
Anne Rice, überqueen of the modern vampire story and a woman whose ouevre has been comprehensively spoofed by Terry, has an interesting comment on the anal-retentiveness of vampires. In her book "Blood and Gold", she introduces a vampire who is trying to break away from killing for pleasure: his method of refocusing the legendary attention to fine detail of the species is to construct ever more elaborate model railway layouts. This vampire is first seen lovingly emplacing a model house, which is built in loving small detail and which even has working, timed, interior lights. As Ms Rice is otherwise a woman of little discernable sense of humour, it is unlikely she did this for a joke: but the juxtaposition of übercool vampires and übergeeky model railways sounds almost like something out of Pratchett! Maybe they both had the same reasoning about the vampire species - they need some sort of outlet for the anal-retentiveness?