I'm starting with a sci-fi story and it will have two sequels, so I'll have three stories, all of them with the same protagonit, but with different characters with him. The thing is that I don't know how I can make each cast unique and not repetitive. I'm still starting, but I have an idea about each of them, but I feel that I'm being repetitive in a couple of things: 1.The three main casts are "normal" people: in the first part they are random guys who ended in the wrong place, in the second part they are the protagonist's "apprentices" and in the 3rd part they are ex-convicts who, along with the protagonist, wants redemption. 2.In parts 1 and 2 the protagonist will have a... difficult relation with another character. In part one it will be with a petty thief. In part two it will be with someone who was a villain in part 1. In both cases THe rotagonist and the other character becomes great friends. 3.In the three cases I dread repeating archetypes, for example, in all of them I have a big friendly guy. Any idea or suggestion? Thank you.