I’m writing a story in the format of an “autobiography” from the point of view of my MC who has a rough upbringing and doesn’t do well at school. In fact he drops out in his mid teens. He’s not dumb as such. Just limited in terms of words, spelling, grammar etc and I’m not sure how to portray that realistically but also still be readable. More of his background: Born and raised in a run down trailer park, filled with poverty. His dad left when he was a baby. His mom is young and cares more about partying and therefore is negligent. His grandfather is around and helps to bring him up but he isn’t a great role model and dies when my MC is around 7 years old. In the trailer park the kids are free to run riot. Little to no discipline. No respect for their surroundings. No real ambition in life I hope I’ve posted this in the correct thread
Well, I'm not exactly an expert in this but if I had to throw in my two cents, a good place to start might be to look into the words he would've known when he dropped out of school. Also consider the words he could've picked up in say his line of work or around where he lives. If you haven't already, I'd recommend reading Flowers for Algernon. Granted, the character there and your character are both very different, and it is an epistolary novel, but it should give you an idea of how to write a character with poor grammar/spelling/a limited vocabulary while still keeping things engaging for the audience.
It's important to remember that you are writing your story, not your character. You might want to make this character your narrator, but that doesn't create a pass for bad writing. Your character in not writing the story. The character is something you've made up to better tell a story.
While this is true narrative voice does have to match the character of the narrator. Good examples include Huck Finn and the moon is a harsh mistress by heinlien
It depends on whether the narrator is the character or not. If the narrator is the character, as in the case of True Grit or some of the other stories already mentioned, then it needs to be done in the character's own words. If it's in first person then the narrator is the character, otherwise you've got free reign to write with a very different vocabulary. Since it's an autobiography, it's in first person.
I definitely second this! Flowers for Algernon's writing style in the beginning is definitely well executed. Do something similar to it and I think for sure it will stay engaging. Also, seeing the details you provided, it's almost certain that the main character grew up with slang and not a care for proper speaking, so it's likely the MC will talk like that.
An example I like for this sort of thing is A Clockwork Orange, where the narrator's voice paints a very clear picture of how he thinks and the limits of his intelligence, even as he tries to convey himself as some sort of misunderstood genius. Little things like having run-on sentences and sentence structure that isn't grammatically correct can go a long way in giving the narration the write tone, if that's what you're going for.
People who are expressive will be expressive, regardless of the extent of vocabulary. A limited vocabulary won't hinder creative expression in someone who is talkative. Someone laconic or inexpressive will be like that regardless of the vastness of their functional vocabulary. Wherever you character lies in that spectrum is how you write him, adjusting word usage to fit while not making it condescending.
I suggest you look up the story "Born of Man and Woman" by Richard Matheson, It's written in the character of a child whose only contact was with two abusive parents who keep him chained up in the attic. It's a classic horror story. https://en.wikipedia.org/wiki/Born_of_Man_and_Woman
If I may give a suggestion, if you haven't yet, read 'Nightmares and Dreamscapes' by Stephen King. One of the main characters is a mentally handicapped man (starts the story as a child) with a severe speech impediment. Might give you some ideas and inspiration.
I will add a few words of caution here. To feel authentically cohesive; the MC's narrative voice should be determined by his age, and the status of his life, at the time he is writing the autobiography. Is he still a teenager in the ghetto, or is he now a wealthy oil baron in his 60's? A ten-year-old child will have a vocabulary sufficient to pass as an adult in normal conversation. People often make a conscious decision to use poor grammar and lackluster vocabulary, their level of education is not a large component of this behavior. When I'm attending a Gala, I speak a certain way. When I'm fishing with an old friend, I speak another way. Traverse a construction site and you may hear a man (who lives in a trailer park) speak like an uneducated hick, cursing and neglecting all sense of grammar. Go have a beer with him and he may confound you with an eloquently delivered dissertation on particle physics or philosophy. Your teenage MC verbalizes the "lingo" in the trailer park, but unless he has a mental handicap, he only speaks the "lingo" by choice. He will know how to speak with more refinement and respect when addressing his friend's mother or any other figure that he respects. Furthermore, how we speak and how we write are separate things altogether. When we write a quick note, we butcher our grammar. When we write an autobiography, we take our time to improve our grammar to an acceptable level. This will be universal for anyone. Your MC's childhood is no different than the upbringing of some of the greatest pillars of literary fiction. We humans tend to be chameleons, adapting to fit in. The trailer park is no exception.
I was going to mention Flowers for Algernon, but I see it's up above. It's unique in that it shows the MC's vocabulary growing through each chapter. I'd say that the main thing you need is to make the people around the MC tell the specifics. Even if the MC misunderstands them, the reader won't. I'm reminded of the beginning of Flowers of Algernon when all of the scientists are explaining the details. That book is so depressing. Really bums me out thinking of its plot arc, but it's an excellent read if you haven't tried it already.