I still haven't read this book yet but want to, simply cause I adore the movie.
Part of why they sound so much older could be due to the struggles they've faced. I know people who face these kinds of challenges at a young age tend to grow up faster than normal, so that could be a factor. Just a thought, but I can't say for sure since I've only seen the movie so far.
The movie is excellent, btw, so I highly recommend it. The actress who plays Hazel is brilliant and if you cry at anything you will cry at this movie.
Yeah, I'm familiar with the actress and I think I would enjoy the movie more. I get that you may be more mature, but at the same time, the language felt a bit stilted in that sense, for me. I've had depression as 18 year old and people always told me that I'm so mature for my age, so I get that aspect of things, but that should reflect context not linguistic, in my opinion. It didn't feel all too natural, but perhaps it's just my personal bias.