My tenth grade English teacher drilled in our heads that there is no such thing as an original plot/idea. Examples: [name_m]Romeo[/name_m] and [name_f]Juliet[/name_f] (obvi) + Twilight, Gnomeo and [name_f]Juliet[/name_f] (lol), Titanic ; The Phantom of the [name_f]Opera[/name_f] vs. Beauty and the Beast vs. The Hunchback of Notre Dame (geez what’s with these [name_m]French[/name_m] people? :P) ; The Hunger Games + Battle [name_u]Royal[/name_u] ; etc. etc. etc.
(In fact, there’s a theory that states that every thought you have had/will have has already been thought by someone else in human history. You’re never going to have a truly original idea.) But! That doesn’t mean everyone has already used up all ideas ever. You just have to be the first to publish it.
What I mean by that is, yeah, we all could have made [name_m]Romeo[/name_m] a vampire and renamed him [name_m]Edward[/name_m] who is hellbent on trying to not drink his [name_f]Juliet[/name_f]'s ([name_f]Bella[/name_f]'s) blood, but we didn’t. Someone else did it first. However, you could be the first to make [name_m]Romeo[/name_m] an astronaut named [name_m]Jackson[/name_m] who crashes an intergalactic party where he meets the beautiful alien princess Ryxssp (or any other weird name insert here).
Plot is nothing without characters, motivation, circumstances, and exposition. We don’t keep reading the same story over and over again because of the plot, but because of those other things I mentioned in the previous sentence. Take fanfiction, for example. There’s a bajillion Coffee Shop AUs. Coffee Shop AUs are neither original nor particularly interesting (i.e. it’s boring). But the way the authors write the characters - how the characters are interpreted, how motivated they are to get a phone number, how they ended up where they are, how well written everything it. This is what pulls people in to read the same plot/idea over and over and over and over and over again.
So what if someone thought of it first? All of [name_m]Shakespeare[/name_m]'s plays are in public domain. Go crazy. (And Dracula. Can’t forget good old Dracula. :P) So what if it sucks or it’s boring? Throw a wrench in the dang thing (or zombie apocalypse, or alien invasion, or long-lost twin brother, or dragons, or whatever tickles your fancy) and fix it until the dam breaks into a river of inspiration. So what if it doesn’t exist in your head yet? It’s gonna and you better believe it.
TLDR; No plot is original. Be the first. Make the characters yours. And, most importantly: WORK IT, GIRL/BOY/PERSON.
[name_f]Hope[/name_f] this helps or inspires. [name_f]Happy[/name_f] writing and have a wonderful day! 