The main characters of my story are four. For approximately thirty chapters the main characters are three and after they'll meet the four. The problem is that during this thirty chapters there is the time necessary to create a balance between these three characters. If I insert a new character in the group, i don't know how can change the balance and I'm afraid that the new character could not insert in the group and that It can seem marginal. For these reasons I would that this character could have a strong personality, but not trite or stereotypical. Then, I would that he's not similiar to other three, but I have not idea where to start. How do you create a new character? Do you follow steps or a scheme?
I usually look at the character's and decide why I need another one. To stir conflict or resolve it. I was watching the old Tarzan movies last night and after three movies they add a new character to stir new conflict. For the first three movies - it's just Tarzan and Jane with the conflict being - greedy ivory hunters. But in the fourth movie the writer's give the couple a son. A much needed twist. Not only does the child bring them joy but he also stirs up a lot of new and interesting conflict. Even adding a new dimension to the character's relationship - they're not just husband and wife any more they're mother and father. But you could also bring in a character to help resolve issues. I remember reading an old children's series in which three girls befriend a fourth - a shy girl who helps to smooth things out between two of the more temperamental friends. Look to the characters and their storylines, examine their needs, that should help you create the character you need to round out the story. You don't necessarily need a flashy character you need a character that suits the situation you've set up for it.
I second everything said by @peachalulu. I don’t think it’s as simple as following steps or a scheme. You gotta read the waves, and intuitively navigate them. Before adding a new character (or a new anything) you have to understand the current balance and take into account what effect the new element will have on that balance. If the new character/item/event doesn’t change the dynamic at all, why is she/he/it even here? In my recently-completed novel, the cast continues to change throughout the entirety of the story. One of the biggest shake-ups comes about halfway through: after a major defeat, one character is left dead, another is permanently incapacitated, and a third quits the mission. The last “main” character joins the team about ¾ of the way through. In my case, the changing cast propels the story onward. There is external pressure, of course, but the internal pressure changes the people involved and changes the course they choose to take. How can they continue on without Such-and-such? What will happen if we add So-and-so to the group? Can we trust this new person? New people bring new skills, new opinions, and new motives. They take the story in new directions.
Much would depend upon what this new character is supposed to do, and what the group dynamic is amongst the existing three. The purpose of the character will largely determine the person's nature, background, skills etc.
Actually this is a good point too, how does genre play in the addition of characters? Example - A new guy in a romance rarely appears except to stir trouble or competition, or jealousy. In fantasy a new guy is never just there - he usually has some skill, or talent or information needed to progress the mc's journey.
Thank you for your advices! Now I have idea about how can I create and insert my new character in the group. Then, thanks to you, I get it that is important the functionality of a character! I thought a lot! Thank you to all! I know what to do!
You stated in your intro that you wish to improve your English, so here I will point out that you used a cardinal number (quattro, four) where an ordinal number (quarto, fourth) is called for. As for your main question, it's a bit more than can really be answered in a single post. The best short answer I an offer is to observe people. Take note of what you actually observe (see, hear, etc) and what those observations make you think about the person's inner nature. You'll build an inner catalog of character elements on the process. It will take time to develop, so be patient. But it is worthwhile, and not only for writing.
I'll second everybody who suggested you build a character around what you need them to do in your story. Will they provide balance? A challenge? Will they upset the balance? Will they be lightearted relief, or provide serious weight? Will they provide support for your main characters? Do they challenge everybody else's comfort zone? Once you have the reason in place for them being in the story, their specific characteristics and personalities will evolve as you write your scenes to include them. Don't try to straight-jacket this process too much at the start, though. You'll end up with functional characters who don't do much more than function. Don't be afraid to allow their personalities to develop.
I agree with most of what others have already said, but I'd add a word of warning: when I come up with a new character, especially a smaller, less significant character, I tend to give them histories as elaborate as those of the MCs. Usually that only helps since it allows me to better understand the character and hence do a better job of writing them, but more than once, their pasts have turned out so interesting and elaborate, their roles have started expanding far beyond what they were supposed to be, robbing space from the MCs and the main plot etc. Sometimes when I realize this (usually pointed out by the Mrs.), I either grudgingly downsize their roles back to what they were supposed to be, and occasionally, if the character turned out exceptionally interesting, I'll cut them from the story, replace them with someone less captivating, and use the interesting character as an MC in another story. Still, it's always pretty annoying when that happens because of all the wasted time and effort although sometimes the end result is something much more and much better than originally intended.
Thank you for the correction! I thank you all for your precious advices! Now I know where to start! You use differet ways to create a new character and reading your adivices and your ways to invent, I understood what is important for my story and for my characters! Thank you!