Let us take our knitting needle-wielding granny, for example. We'll call her Rosa. Rosa likes to knit. In fact, she is a champion knitter. World renowned. But in the night-time she puts those skills to a completely different use. Assassination.
How much more interesting is that, than a simplistic grandma that spends her days (and nights) knitting and being a sweet old lady who'd never hurt a fly? Significantly more. That's the answer. I want a story about Rosa, not that lady. Rosa naturally creates a conflict in the story. Whether she is the protagonist or the antagonist, she'll drive that story.
That's what your character should do. The conflict in the story should react to them, not the other way around. They should drive the plot.
Of course, that doesn't mean that there can't be conflict that our main character just happens to land in. However, they still have to drive the story. They have to be in charge.
Take Katniss Everdeen, from The Hunger Games for example. Yes, the Hunger Games have gone on for years without her. No, she didn't start it. But her conflict began because she volunteered for the Games. And that's interesting. Because it defies expectations.
Would you really expect a teenager to volunteer to go into a killing game? No, you would not. You understand that isn't normal (unless you're a Career, which is a completely different thing) so when Katniss volunteers to take her sister's place, it matters much more.
Even after she volunteers, she drives the story. Her actions control what happens in the plot. I won't give away any more spoilers, however.
It can be the character defying expectations in that way, or just in personality. Or in their job, like Rosa. You can have so much fun with it. And it doesn't have to happen at the beginning of the story. Sure, that pulls the reader in, but you could have a character that didn't defy expectations right up until the last minute. It might be difficult, but it'd be cool and unexpected.
So what are your favourite characters that defied expectations? Did you agree with what I said above? Comment below, and let me know!