While that is a criticism of the show, one definitely gets a feeling through the first few episodes of the series that Mitchell is darker on purpose. The viewer learns early on that the vampires have some sort of weird, powerful network in the city, and they tend to stand far more on the side of evil (even if they're cops) than good. Mitchell doesn't approach the evil side, but unlike George and Annie, he is surrounded by many more of his own kind and has to contend with that social network as well. Plus, as we're told early on in the series, the vampires tend to think something big (and perhaps bad) is about to take place. It all necessitates Mitchell's being more dark, but his character makes the show a lot less fun.
George and Annie do know others of their species, just not as many, and werewolves and ghosts apparently don't have large social circles. Still, their encounters with their own kind are serious, heartfelt, and sometimes evil, but when they reenter "normal" society, they are able to maintain a far more lighthearted nature, and one that seems to fit better with the overall sense of the show.
Going beyond the supernatural, Being Human does deal with a lot of real, down to earth issues, everything from dating and relationships to work to one's place in society. Watching these three people trying to figure out who they are, and how they can best approach the world at large is fascinating, and at times truly heartbreaking. The best example of this is with Annie and her having to watch her one-time fiancé dating someone else while she is still in love with him.
Though not always a perfect mixture of the natural and the preternatural, Being Human does manage to do a decent balancing act in the first three episodes of the season. Enough questions are asked and avenues opened for exploration that it could be fascinating to see where the show goes in the future. It could very well wind up being Buffy-esque (and certainly owes a lot of itself to Buffy) and remain highly enjoyable for years to come. At this point though, it is simply like, but not love, at first bite.
Being Human premieres on BBC America Saturday, July 25, at 9:00pm.