Right now I am in the process of writing a story (aiming for novel) based on a teenage character which would obviously place it in the teen fiction genre. However, I've decided that I want to make it an adult novel without making my character too old (due to the plot line). So, how old is old enough to be out of teen fiction?
You can write a story with teen characters that's an adult novel. Cormac McCarthy won the National Book award for All the Pretty Horses, and the main character in that is 16-years-old. He wrote a novel called Blood Meridian, which is in no way a "teen-fiction" novel, but the main character in that was 14-years-old. The age of your character really has nothing to do with whether or not it's teen fiction or an adult story.
and don't forget the classic, 'to kill a mockingbird' in which the protag is young jem and the story told by his even younger [from 8-10/11 at the time] sister, scout...
There is no implicit correlation between the character's age group and that of the intended audience.
The story is about a young poor girl who gets caught up with an older man (late 20s off of the internet) who is bent on getting a large sum of money from his family, but only if he marries (he wants someone who he can "train" to do things his way) and her internal struggle with choosing between family, money, and love
nothing very original there, but anything can work if it's written well enough... that said, if you want to hit the adult market, just make their ages more adult... i don't see any good reason for her to be a teenager, do you?... she can't be all that young and be able to marry, anyway...
The age of the characters isn't what distinguishes a novel as a teen or adult novel. The age group it's for is simply 1) who you mean for it to be read by and 2) who enjoys reading it the most, imo.
I think you can make it an adult-oriented story just by introducing more adult characters in it. The way you manage through adult-teenager relationship can be very adult itself. The reader will find someone to identify themselves with, not necessarily the teen protagonist. The main character in my novel for example is 17 when the story begins, and at the end of the book he's 28. The main plot is his relationship with his mother (who's 39 to 50). I am 34 so I'm just in the middle and can stretch my neck to his generation but also to his mother's. Maybe what works best when writing about a teen, is place the character in your own generation (my main character is 17 in 1989, so I can talk consciously about fashion and lifestyle). That itself would make it adult-oriented, cause you can work with nostalgia. That's just my thought of course.
