Not being a published author, I refrain from writing posts on how to write a successful story. However, as an avid reader for fifty plus years, I feel qualified to write about what makes a story stick with me like a hot bowl of oatmeal on a cold winter day.
Strong secondary characters form the foundational framework to support the main character during whatever trials and tribulations he/she must face to be successful. None of us go through life completely alone and without support. Even the lowly dandelion seed must rely on the support of the wind to carry it to its new destination or it would simply fall to the ground accomplishing nothing.
Supporting characters need to fulfill a variety of roles. They should be there to lift up the main character when he/she fails. An understanding mentor who can teach them what they can't learn on their own is sometimes needed. I always enjoy a character capable of providing some comic relief to overcome those parts of a story that can mire us in sorrow.
Typically, the main character is someone who does not want to do what's necessary and it's up to the secondary characters to push/pull or even trick him/her into action. They can consist of family, friends or just someone met along the way.
Of all the stories I've read, the ones with a strong cast of supporting characters are the most memorable. My favorite series of all time, Robert Jordan's Wheel of Time, has so many secondary characters, I lost count!
This is just my opinion, of course, but I think a well thought out cast of supporting characters will make any story more memorable.
Thanks for taking the time to read. As always, any comments or opinions are welcomed.