The literature here deals with this dichotomy -- how you deal with the darker sides of masculinity in the post-Bly post-'90s sexual anarchy we've wandered into -- in different ways. Those Anita Blake books deal with it by turning the woman into a third, inherently feminine creature of darkness, a succubus, equal in power to the two operating male archetypes. Stephenie Meyer's Twilight books get really weird with it pretty early on, but basically frame the werewolf/vampire triangle as a basic coming-of-age story in which both versions of masculinity are necessary in order to fully awaken the woman's sexual maturity, flowing into and out of each other and breaking down the walls between them even as she's taking on the roles and habits of everybody else, like every teenager. Harris, in the source material, works the triangle as a negotiation with darkness, making both suitors passports into the areas of darkness necessary to reclaim all territory, dark and light, for herself. To me, this seems healthiest, but they're all the same kind of myth.
Why's it happening again? Why on earth is our culture playing out entirely vampire boyfriend/werewolf boyfriend right now? And I'm not just saying this because Twlight came out yesterday -- these three series of books I'm talking about started in 1993 (Anita), 2001 (Sookie), and 2005 (Twilight) and pretty much have ruled the bestseller lists since then, even with the variances in quality, readability and WTF between them; seven of the eight Sookie novels are bestsellers pretty much nonstop, which is not something that ever happened before. I think it's pretty easy if you follow the line of blood: The war and the Greatest Generation's reassignment and recapitulation of gender roles becomes the uphill battle of the '50s and the glorious global shout of the '60s becomes the delirious sexual abandon of the '70s becomes the cruelty and sexual artifice of the '80s becomes the total AIDS-related sexual freakout of the '90s ... and we grew up in that, doing the incredibly dangerous undercover work of becoming healthy sexual beings that people have been doing since there were people, with all that crazy on top, mediated for the first time by television telling us back to ourselves in realtime and the endless fucking Baby Boomer retellings and nostalgia and music videos disguised as feature films. We became men and women in the middle of that shitstorm. Vampire Guy/Werewolf Guy is just us telling that story back to the world and trying to decide what to do next.