When shows change up characters, replacing older characters with newer ones, usually it's a signal of a show's decline.
Look at the cast changes of shows like "ER" or "Law & Order" over the years.
"Lost," (ABC, 9 p.m.) however, is one of the few series that has jettisoned some of the lame characters (Boone, Shannon and so on) and replaced them with characters far more interesting.
Ben, Juliet, Miles, Desmond, Mr. Eko and others are all characters that joined onto the show after the first season and became fixtures during the time they were on (even if some of them were killed off later). Even bad characters like Nikki and Paolo (remember them?) had a great episode devoted to their deaths.
Perhaps no character has been more of an enigma than Richard Alpert (Nestor Carbonell), the seemingly immortal man who apparently was once a slave and now serves as the advisor to whomever serves as the island's leader. Tonight's episode is supposed to give us Richard's backstory and solve some of the mysteries surrounding him.
It's safe to say that for "Lost" fans, this is one of the most anticipated episodes of the season. (At least until Ep. 15, which reportedly has virtually none of the cast and tells the history of the island).
It's a testament to the show's writing that they could just have this guy show up one day, and work him into the story in such a way that he creates an air of mystery in a series that's all about mysteries. And it's a tribute to Carbonell that we want to learn more about this character.
TUESDAY'S BEST BETS: DVR alert! "Lost" runs about six minutes long tonight, so be forewarned if you are taping it. It's followed by a summary special of "V" at 10:06, which boils together the highlights of the four-part miniseries that ran earlier this year. I don't have high hopes for "V," since "FlashForward" had a similar layoff and took a ratings hit when it returned.
"American Idol" (Fox, 8 p.m.) is two hours tonight, as is "The Biggest Loser," which runs at the same time on NBC and is followed by a new "Parenthood" at 10 p.m.
The CW has new episodes of "90210" and "Melrose Place" from 8-10 p.m., while CBS is all reruns.
On cable, there's a new "Southland" at 10 p.m. on TNT. Also, "Justified" (FX, 10 p.m.) is being called TV's best new show. While it's hard to say that in a season that has given us "Modern Family," "Glee" and "The Good Wife," "Justified" certainly is worthy of some praise.