Every new television season has to come up with ways to draw in more viewers without losing ones they have. For some shows, context is a big hint. Doctors can travel on trips that bring medical help to those who need it. Lawyers can be hauled up in front of the Bar on charges. People can get transferred to another location, or as a result of being married to someone who is. Quitting happens, as does firings. The reasons may or may not be unique to the job.
Oh yeah, and there's one way to draw in viewers quickly (and keep water cooler talk going)-death. In Smallville, Jonathan Kent died of a heart attack. Now granted , that storyline fell in line with the comic book. The Sopranos saw a major character get shot, and could die. Uh here's a news flash-the show is about mobsters! Tony's own mother tried to kill him at one point. When Nancy Marchand died, however, her character had to die as well. 24 has a habit of dropping folks like flies. Then again, the show has to do with terrorism. Perhaps one day I will get the Sean Astin death scene out of my head. This reminds me: Leo McGarry had one heart attack on The West Wing. Perhaps that suggests how to handle the daeth of John Spencer?