A big problem of multi-published writers is coming up with unique characters to tell their not-so-unique stories. If you are a fan of an author who's been around a while, you may have noticed their characters have many of the same qualities. Jaded career women who can't commit because of past hurts. Physical male characters with tattoos and bruised egos they cover up with hard language and hard living. Aging debutantes with haunting pasts that keep her from drawing closer to those she loves.
I have nothing against formulas, especially ones that work. Writing is a business and we need formulas to tell us what works, what doesn't, and most importantly, what sells. When readers go into a bookstore for the latest Grisham or Clark or Patterson because they know what to expect. At least they have an idea of what they're in for.
The writer must be wary though that each character isn't a barely disguised rip-off of the last hero or heroine. In my books I tend to have one older female character with plenty of wisdom and opinions she isn't shy about bestowing on anyone within earshot, especially my heroine. I love this type of character and I think I portray her well. But I don't want every book to be littered with the same stiping aunt or grandmother, just with a different name and hairstyle.
How do writers give the reader want she wants and expects without ripping off their own last bestseller?
Stay true to character. Pay attention to detail. You may know several hard fisted, truck drivers with Mom complexes, but they are all individuals, regardless of their similarities. Give your characters a unique personality even if you've tackled their type before. It's all in the degrees, not to mention the different situations in which you put each character.
Readers will resent you more if your book does not live up to their expectations. Keep surprising them. Keep delighting them. And give them what they've come to expect from you, a fantastic story.