You already have many answers but I love dropping my experiences here as well. I really appreciate you asking! 1. There isn't a set reason or cause for stuttering. Many young children experience suttering but it usually wears off/goes away after couple of months but for some it stays longer and doesn't go away. Stuttering is definitely not related to trauma or traumatic events, even science isn't really sure of the causes or origins of stuttering, last time I checked. I like to joke that I started stuttering when I was able to overthink the everliving f out of my life, so from a very young age – maybe that's true but I think it just developed without a specific cause. 2. Generally, stuttering is something that I can't make rules about. So much is about how many people, what I need to say, how I need to say it and so on. After a time, I learned to be more careful with specific words and letters, syllables etc. since, well, they would never go out easy or completely screw me over. The worst letters/sounds for me are: d/t, w, s/z and k/c. Too bad that my name starts with one of these sounds which links introductions of any kind to panic, anxiety, shame, feelings of guilt and so on. However, I found that the main issue aren't the letters but the sounds or syllables. I have little to no problem with words that start with "da"/"di" sounds but I – for the live of me – don't seem to be able to get words out that start with "deu"/"det" sounds. Troubled words and sounds vary from person to person and I don't think many will get angry when you choose your own for your character (or choose answers or combinations from comments etc.). 3. Stuttering is very indivitual and much depends on current mood, extermal influences (like noise, weather, people, surrounding, etc.) for me. When I'm alone, it's almost completely gone, I usually talk like a waterfall with myself. The stutter is very weak when I talk with one person and the severity increases with the amount of people listening to me or being present. Something that makes stuttering worse for me is when I'm ina hurry or expected to perform. This includes using radios when working backstage in a theater etc., introducing myself in a group where everyone just quickly says their name and age where I can't relax and get used to the ambiance. The absolute number one thing that makes stuttering worse for me is when asked to read something from a book or any other "defined" text (excuse my english ;) because I have no room for variation. If I know a word won't work, I can't use a synonym because this would deviate from the text and everybody will notice. 4. I don't know what it feels like to not stutter so I don't know I'm giving you all answers that you were looking for but I can most certainly try! I have recently realized that stuttering kind of feels like walking over a frozen lake. You can sometimes see weak spots that you shouldn't step on and other spots that will support your weight. You can analyze your next step – and it sometimes works out great – but in the end you only know if it works when you take the next step. When the ice cracks below your step, speaking suddenly becomes a reaction test. Can I skip the word? Can I find a synonym for the current word – a different spot on the "frozen lake" that maybe doesn't break that easily? Am I able to find a different term for it? Will others notice? Should I say something about my stuttering? Will others judge me? (This is when my social anxiety usually kicks in lol) – and all the way to questions like: Why can't I even say my name AGAIN?! One of my worst stutters was 40 to 60 seconds, I can't recall because it felt like hours and you just listen to yourself not able to say a word. I don't know if others are judging me but I'm downgrading and judging myself enough at this point so what does it matter? I learned that whenever I speak, I basically write an alternative version of my speech in my head while talking to always have synonyms read if I could need one. That's because I usually see a block/stutter coming about one to two seconds before saying the word/sound. That is why speaking is more exhausting with a stutter. That's why my words are sometimes interrupted by long pauses because I need to structure my next phrase, forgot what I was saying and so on. Stuttering aren't just the blocks and repeated sounds but also the overall mentality/mind set when it comes to speaking. ––– I hope this helps you! If you have any questions, feel free to ask here or message me, I'd be very happy to answer and help you understand stuttering better :) Cheers and good luck with your book!