Not all Vampires believe they are supposed to prey upon whomever, wherever, whenever. Some, prior to being Turned, were strong in mind and in body, or perhaps their Sires simply had the foresight to guide them along a path that wouldn't lead them to immediate ruination.
Some time ago, a group of Vampires decided they would start a Council of sorts, searching the world for Vampires who weren't slaves to their primal natures, and who actually had an interest in controlling the outbreak of Vampirism, and reserving it for those who would help Vampire kind perpetuate itself in secrecy, without drawing attention to themselves from the humans.
Obviously, Vampires being what they are, willing participants were hard to find, and one hardly wants to try and force a beast to act like a civilized, sentient being. The search continues, but a handful have been found who have the intelligence, self-control and presence of mind to endeavor towards their own self-preservation, along with that of others of their kind.
The Vampire Council was founded by Sir Alexandru Danesti, an otherwise obscure Vampire who maintained said obscurity by keeping a low profile. Maximillion X, another individual who believes in using his gifts to perpetuate the fullest extent of his Vampiric immortality, has been on the prowl for other Vampires who could help the Council achieve their goals, as well as doling out vigilante justice on those who're drawing the attention of the Vatican, along with the general public, to the existence of Vampires.
This storyline would revolve around the 'Civilized Beasts', and the lengths they will go to survive, working their way into positions of status and power, infiltrating government offices and climbing up the corporate ladders, seeking a future for Vampires that doesn't end abruptly as ash being scattered to the wind.
Those willing to aid in this cause, be they Vampires or Humans who somehow know of this cause and are in support of it, would be encouraged to participate, in whatever capacity they feel they can.
Anyone who is a fan of espionage, politics, psychological thrillers (etc) might find this Plot Device to their liking, a way to make their mark in the Hellsing RPG world without having to be a crazed, bloodthirsty beast.