There are plenty of tropes in teen dramas that all fans know. Pretty Little Liars was known for its plot twists, cliffhangers, and mysteries, which are right up among those most frequent tropes. It was more surprising for there to not be a plot twist than for there to be one.
Pretty Little Liars was one of the most popular shows while it aired and one of the best on Freeform, according to IMDb. As a teen drama, it exciting and mysterious even though it had its share of continuity errors. As compelling as some of the show's storylines could be, the mystery drama did not avoid every trope.
Uses: Teen Detectives
It isn't uncommon to see teenagers solving mysteries in teen dramas. Discovering secrets was a major part of Veronica Mars and Riverdale. The Liars are always searching for answers to the biggest and scariest questions in their lives, which always leads back to one question: Who is A?
This person controls them from behind a screen or from within a black hoodie. With their lives on the line, Hanna, Aria, Spencer, and Emily become teenage detectives as they search to know the several hidden secrets in their lives.
Avoids: The Parents Are Dead
It seems like most of these teen dramas involve at least one or two storylines where someone's parents either die or are already dead when it begins. For several seasons all the main character's parents are alive.
Only in later seasons do some of their parents pass away or are killed. The parents being dead is not the instigator at the beginning of the series that justifies anyone's actions.
Uses: Teacher/Student Relationship
Also portrayed in Dawson's Creek and Riverdale, the teacher/student relationship was not a new storyline. However, Pretty Little Liars makes some very controversial choices toward it. Ezra didn't only meet Aria before school started; season four revealed he was already aware of who she was and her age. Ezra had been stalking the Liars to write a true-crime book.
Additionally, their relationship has several other problems, many of them stemming from the fact that Ezra is Aria's teacher, and their relationship begins with Aria as a minor. It could also be said that Pretty Little Liars glorifies and romanticizes the illegal relationship by having Ezra never face the consequences of his actions. The two even get married in the series finale.
Avoids: Teen Pregnancy
Spencer and Toby do have a pregnancy scare during Spencer's college years, but none of the main Liars ever have a pregnancy storyline during their time in high school. Given how much time was spent searching for A, a pregnancy storyline amidst school, mysteries, and home drama probably wouldn't have fit.
Still, the series took the opportunity to create a pregnancy storyline with Alison later on. However, it is actually quite a disturbing saga as she is forcibly impregnated with Wren's sperm and Emily's egg.
Uses: Bullying
Pretty Little Liars uses bullying as a focal point. There would be no A without that aspect. Mona becomes A in part because of the way Alison treats her. Alison, before she left town, was not a nice person. She looked down on others and always insulted Mona. She even hurts her own friends at different points.
Having had enough, Mona creates A, a way of gaining control over Alison. She later uses that persona on the other Liars when she feels her friendship with Hanna is threatened. A lot of the series is about manipulation, and nearly every character has a role in that.
Avoids: Financial Differences
In a series like The O.C or One Tree Hill, the' financial differences show some of the conflicts between characters. Pretty Little Liars avoids that by keeping their show in a small suburban town.
Everyone dresses unrealistically well for school, and it is rare to show anyone wears the same outfit twice, except for A's black hoodie. Finances do not play a significant role in the show's events, and it is not a way to separate the girls from each other.
Uses: Time Jump
The girls graduated high school; now what? Five years later, the Liars return to their roots, reuniting as well as falling back into some old patterns. The time jump gives everyone the chance to grow up a bit, letting them experience life outside of the constant fear A brought.
For a few years, they could find normalcy in life again, even if it did take some time. It gave characters time to get into new relationships that would bring drama to the storyline while also introducing new villains. One last time jump in the series finale prepares for Aria and Ezra's wedding. This is not new territory for teen dramas.
Avoids: Supernatural
Ravenswood may have had ghosts, but the supernatural doesn't appear in Rosewood. Even if the show's events are not realistic, they are kept in a reality that fans can relate to. Ordinary life and drama may be exaggerated, but there are no witches, ghosts, vampires, or werewolves walking the streets.
Instead, Pretty Little Liars uses technology and sleuthing to show how Charlotte, Ezra, and Mona know so much about Hanna, Spencer, Aria, and Emily.
Uses: Adults Are Useless
For the most part, the adults are left in the dark about A. The girls don't inform their parents out of fear about what A is capable of. Instead, they handle it themselves. The police, in plenty of ways, are either corrupt or completely useless. The parents can't do that much against A, so it falls to the girls.
Although the parents tried to help when they could, the Liars could easily leave their backyard prom to find Alison. They got away with several things that their parents may not even be aware of.
Avoids: Central Love Triangle
There may be a love triangle after the time jump, but there was never one that lasted the entirety of the show. Hanna finds herself caught between her fiancé Jordan and ex-boyfriend Caleb while Caleb is dating Spencer. There are also times when it appears that Emily could be caught between Paige and Alison.
However, in the series's span, these are brief and do not make a lasting impression. There is not a point where there is a triangle from the beginning of the show that lasts all the way to the end.