on Jane Friedman site:

Some writers believe that their protagonists must be likeable in order for readers to care about them.

And of course there’s some truth to that, which is why screenwriters adhere to a formula called Save the Cat: Having your protagonist do something kind or admirable or just generally awesome (like saving a cat who’s stuck up a tree) is indeed one path to your reader’s heart.

But the literary world is full of so-called unlikeable protagonists—the sort of people who not only fail to save the cat, but might have run it up the tree in the first place—that readers nevertheless care a whole lot about.

In fact, making your protagonist too good, paradoxically, is an excellent way to make your reader not care about them at all.

Not only because such characters don’t ring true (we all have our foibles and flaws) but because, generally speaking, we don’t turn to fiction for stories about perfect people.

What really makes us care about fictional people are the same sorts of things that make us care about real ones: understanding their soft, squishy underbelly, otherwise known as their vulnerabilities.

Here are three different types of vulnerabilities that will pave a trail straight to your reader’s heart.