oh my gosh i just checked this since like forever! i lost motivation for this since it was only my two friends reading this so i just dropped it. thank you lots for the response, and im not great with advice but here goes:
introduce the characters youll visit again the most in the exposition chapters,andesine, apophyllite, emerald, covellite i think were introduced in the beginning since theyre the key characters.
as to how, situations in where the mc needs help, they can think 'ah! i bet [yeet] would be great help!' or when the mc is just roaming around or maybe in extreme situations where the mc is in danger, cOugh lunarians, a new character can be introduced there and rush in to help out of the blue. any situation can work really, it just depends on how it is worded. carefully intertwine the character into the story. instead of saying 'Out of nowhere, [yeet2] came to the rescue!' it can be improved to 'In the corner of mc's eye, [yeet2] came to the rescue!' little changes can make big differences, is what im tryna say.
last thing for now, the mc cant get along with everyone! when meeting new chars dont be afraid to spark conflict for their first meeting. this can later be resolved through forgiveness or they can stay enemies. it makes things more lively. perfect is boring, yknow!
ill gladly answer more questions and ill continue this story. thank you again for this, gem!