Hey, nice of you to include a stuttering character and to come to us with questions. Like others have said, there are a lot of different ways to stutter. The prolongations and repitions are the most well known traits but I wouldnt say they are prevailing. A lot of people have silent blocks, which is when they vocal chords basically spasm and lock up, unable to come close enough to vibrate and produce sound. Other types include when someone repeats the same word or sentence because they cant get past that one tough word. These are known as running starts. some examples: "W-w-w-watch o-u-u-u-t!, "W...w....wa..tch ou..out!". "He's head-d-ed for the...He's headed for the r....... He's headed for the rooof!!" But to be honest I think the majority of stuttering is more internal than external. One person has described it as, "Stuttering is what we do when we try not to stutter." So depending on how comfortable the character is there can be a ton of secondary things such as poor eye contact, trying to push out the words through force, trying to sing them out, whatever. But if you want to show this character as someone who isn't overly bothered by his stutter then you can focus more on the overt characteristics. The King's Speech is honestly a pretty good example of what it's like (and its pretty entertaining to boot). Also, a lot of people who stutter substiute words they are aboutt o get stuck on for words they feel they can say in the moment. This can produce some interesting vocabulary choices and could be fun to experiement with. However this is considered to be an avoidance behavior and depending on how comfortable you want to make Julio with his speech he might not use it much. Maybe for key situations.