“Bloodthirsty” is essentially a werewolf movie, but it’s also more of a character piece than a creature feature. That distinction isn’t necessarily a good thing though, since you can only build-up a monster movie so much without delivering a halfway decent monster, werewolf or otherwise. The makers of “Bloodthirsty” spend more time trying to highlight the dark side of Grey (Lauren Beatty), an anxious singer/songwriter who’s stuck on a delivering a sophomore album that’s worthy of her hit debut. Unfortunately, “Bloodthirsty” isn’t as relentless or as disturbing as its name advertises, so it doesn’t really matter how often we see the monster on the movie’s posters. At the same time: while psychological horror may be a fine way to dig into complex personal traumas, “Bloodthirsty” barely gets inside its antiheroine’s head.