A lot of the time when side characters are focused on, it feels like it's just there to pad out the story or was written JUST to give them something to do. It's hard to make it feel like an organic part of the story.Which is why they should just take part in the main story. You don't have to give them major focus or character arcs, just let them interact with the plot. If writers just did this, nobody would complain about characters being "wasted" or "underutilized".
