Throwing a much beloved character into a situation deemed unreasonable or unrealistic by a faction of the show's viewers has been known to cause a landslide of rebuke to rain over the show's writers. For example, in the House season finale, House, in a fit of rage and frustration, crashed his car into Lisa Cuddy's dining room. It was the moment that spurred a combination of derision, shock, and astonishment from a very vocal contingent of fans.
Regardless of the consequences, writers need to stay true to their vision. Viewers might not like the much beloved character cheating on his spouse, getting blind drunk, or crashing his car into a former lover's home. But if it serves the story, there is no reason it shouldn't happen. Eventually, the much beloved character will be redeemed and all will be right with the world.
Then there is the case of the actor portraying that beloved character committing the most grievous of transgressions -- leaving the show.
What if said actor's contract is up and he or she decides, for whatever reason, to depart, relegating the long-standing character to the dustbin? In some cases, the show will soldier on with a minimum of fuss. A perfect example is the classic sitcom M*A*S*H. Colonel Henry Blake (McLean Stevenson) was killed off at the end of the third season and Wayne Rogers, who played Trapper John, also departed after that tour of duty. These characters had solid back stories and were ingrained into the viewers' collective consciousness. But being forced to do without them was a challenge the producers and writers met head on with great success.
Blake and Trapper's replacements were markedly different from their predecessors but it didn't take long for them to find their niche in the ensemble. B.J. Honeycutt (Mike Farrell) came aboard as Hawkeye's partner in crime: a kinder, gentler, less flappable soul than Trapper and, in some ways, more sympathetic and likable. Sherman Potter (Harry Morgan), a crusty veteran of two wars was brought in as the new commander of the 4077th, a character more assured and authoritative than Blake ever was. The change proved beneficial to M*A*S*H, which went on to last another six seasons.
That leads us to a more recent example of an actor bailing out of an established show, this time with much more volatile results. We'll use House as an example again. Lisa Edelstein, who played Dr. Lisa Cuddy for seven seasons, announced she would not be returning for an eighth. No explanation was given for her decision but it's been suggested that her contract renewal talks did not go as she would have liked.
Her fans, a passionate crew (to say the least), set Twitter afire with their rants. No one associated with House was safe from their complaints, cries, and scathing diatribes against the producers and the show itself. Their vows that they would NEVER WATCH THE SHOW AGAIN IF EDELSTEIN DID NOT RETURN were repeated ad infinitum.
The thing these folks should remember is that the show revolves around Gregory House. It is about his journey and how he relates to those around him. If Hugh Laurie were to leave (which is a distinct possibility after season eight, when his contract is up), there would be no show. Period. No matter how popular the peripheral players are, House is the sole unexpendable character in the show.
It remains to be seen if the writers for House and Gray's Anatomy (which recently lost Patrick Dempsey when his contract expired) will take a cue from M*A*S*H and use the departure of a popular character to move their stories forward. Hopefully they, too, will rise to the challenge.