1. The main characters have graduated from high school
Sorry, Glee, but in our estimation the #1 sign a teen TV show is headed for obsolescence is graduation. Take Veronica Mars. After two fantastic seasons, the cult girl-detective series opted to split the season into two ongoing mysteries in a misguided attempt to attract more viewers — and added two shrug-worthy characters in Veronica’s college classmates, Parker and Piz. Although we could never hate this show, we have to admit the quality nosedived once Veronica moved on from Neptune High, with its evil rich kids and sinister class divisions. But Veronica Mars is hardly the only show that lost its touch when the characters moved on to college. Remember Beverly Hills, 90210 around the time Dylan meets his faux little sister and Ray Pruit shows up? Need we even go into the specifics of Saved by the Bell: The College Years?
2. Every possible couple has been exhausted
Gossip Girl should have known it would need a larger cast of regulars to support its level of bed-hopping. When Blair has already dated Chuck and Nate; Dan has tried to make a go of it with Vanessa, Serena, and even Georgina; and even little Jenny has freaked us out by kissing Nate and losing her virginity to Chuck, her would-be rapist, the couples stop making sense. That’s when we get mismatches like Dan and Blair, and Vulture has to go and make an interactive chart of who’s fooled around with whom. But while Gossip Girl is perhaps the most egregious example of this tendency, plenty of other teen TV shows have fallen into the clusterfuck trap, from That ’70s Show to Saved by the Bell to Beverly Hills, 90210.
3. The lead cast members have left the show
Speaking of things 90210 and That ’70s Show share, both kept on going after they lost lead actors. In the case of the latter, Topher Grace and Ashton Kutcher declined to return for the retro sitcom’s eighth and final season, leaving the show without its protagonist and comedy relief/eye candy — not to mention its two biggest stars. Josh Meyers’ Randy Pearson was cast to fill the gap, but the fact that we had to Google to find that character’s name speaks to how effective that substitution turned out to be.
Shannen Doherty, meanwhile, left 90210 after only four seasons amid reports of on-set tension, and the remainder of the series’ ten-season run was marred by futile attempts to replace Brenda Walsh. First we got Valerie, then we got Gina, but those bitchy brunette newcomers could never match Brenda for neurotic, teenage relatability.
4. Subpar minor characters become series regulars
Things were getting pretty desperate for The O.C. by the time it killed off Marissa Cooper (resulting in the departure of Mischa Barton, a casting change that made it yet another teen TV show that lost a lead actor). But nothing portended its doom more than the promotion of Marissa’s younger sister to the status of a series regular. When we met Kaitlin Cooper, in Season 1, she was a horseback-riding innocent who eventually disappeared to boarding school, played by Shailene Woodley. By the time she resurfaced midway through Season 3, she had been transformed into Willa Holland and was just as conniving and debauched as everyone else on the show — which was a convenient, if totally disingenuous, way of transforming her into the new Marissa. See also: Gossip Girl, which shares a creator with The O.C. in Josh Schwartz and attempted to breathe life into Blair’s cardboard cutout prince, Louis, because (once again) there was nowhere else to go after her millionth break-up with Chuck.
5. The show’s most beloved couple has gotten married
As fans of The Office will have to acknowledge, this phenomenon isn’t exclusive to teen TV shows — but boy, do they love to marry off their long-standing couples years before it’s realistic, when the cycle of break-ups and reunions has become unsustainable. On Boy Meets World, for example, Cory and Topanga’s relationship had been evolving for five whole seasons by the time she proposed to him. By then, the characters were in college (see Sign #1), and there was so little drama left to wring out of the storyline that it took another season and a half of fits and starts to actually get the couple hitched. Saved by the Bell pulled a similar stunt, reviving Tiffani Thiessen’s Kelly Kapowski and pinning all of the ill-conceived show’s momentum to casting on-and-off high-school sweethearts as a love story for the ages.
6. The love triangle won’t die
Love triangles may have more inherent dramatic potential than boring, old monogamy, but that doesn’t prevent them from getting old fast. And, for some reason, teen audiences seem to eat them up, as such cultural phenomena as The Hunger Games, Twilight, Buffy the Vampire Slayer, 90210, The Vampire Diaries, and Dawson’s Creek, would suggest. While two guys fighting over a girl (or two girls fighting over a guy, less common in this teen-girl-fantasy-driven genre) can be entertaining, a love triangle that won’t die is the sign of a show that’s hurting for new ideas. Case in point: Felicity, which grew so attached to its Ben-Felicity-Noel triad that it even devoted an entire series of episodes to exploring what might have happened if the title character chose her RA over her high-school crush.
7. All of the children in the family have grown up
Probably because teenagers are utterly uninterested in the lives of adults, teen TV shows and family sitcoms only rarely overlap. But when they do, they’re vulnerable to a problem similar to the one that faces series whose characters graduate from high school: Suddenly, there’s no reason for the teens in question to continue living under their parents’ roof, and when writers contrive to make sure they do just that, the results often feel forced. It didn’t make a whole lot of sense for The Fresh Prince of Bel-Air‘s rich, successful Carlton to end up at home for college, attending the fictional University of Los Angeles. And it was pretty funny when he and Will moved into the family’s pool house — which basically didn’t exist until they relocated there in Season 4. How about Hilary, who was supposed to be more than five years older than both of them yet was always hanging around the mansion, despite a bafflingly successful career as a weather reporter and talk-show host? Thankfully, the show knew to call it quits when it was time for Ashley to start college.
8. Killing off characters is no longer surprising
Nothing shocks viewers like dooming a TV character to sudden and untimely death — and we’ve got the utmost respect for writers who, like Joss Whedon and Terence Winter, aren’t afraid to shake up our expectations with a surprising (yet believable) demise. A storyline that involves a main character’s death tends to be even more shocking when the victim is a teenager. That is, unless you’re watching the darkly romantic British series Skins, which avoided many of the above pitfalls by switching out its cast for another set of 16-year-olds every two seasons. The problem was, creators Bryan Elsley and Jamie Brittain made a habit of axing one main character per cast, and by the time they bumped off a teen from the third group, we saw it coming.
9. The protagonist has died. Twice.
Speaking of Joss Whedon, even he could get a bit carried away with killing off his characters. The good news is, this will probably only ever be a problem for Buffy the Vampire Slayer.