Okay, so it still just wasn't dark enough for me. Sorry. SOMEONE NEEDS TO DIE....and not some "the show is going downhill, star leaves to go into the movies" sort of thing. I am talking one of the main characters. Kill one of 'em off. And make it totally nasty. Something so horrendous, you get mad, sad or go into shock. That should change things up a bit.
ER is notorious for this kind of stuff. Mark Greene died of brain cancer, the [tinfoil] surgeon bald guy got squashed by a helicopter (and after previously losing an arm to a tail rotor LOL), who else. Anyway, keeps the show alive sort of. Look at the cast now compared to day one. I don't think there is a single charachter left but it is still watchable for some reason.
Greg
They pretend to be ready to kill off one of the cast. Yet everything will work out.
In his previous shows, Joss Whedon has not had too much of a problem with killing off central characters to keep things interesting. He is almost notorious for it. For example, the chief supporting character on Angel was killed halfway through the first season despite being quite likeable.