She has a secret: she can see the threads of fate clearly.
She has a secret: whenever a black cat appears, she is bound to meet someone destined for her.
She has a bad habit: she loves playing the selfless saint and urging people to do good deeds. But don't agree too easily. Think it through carefully, or you might end up unlucky at best, and utterly destroyed, body and soul, at worst.
She has one biggest secret: she knows everyone's secrets.
A few other things: 1. I'm terrible at writing blurbs. There is very little romance for the protagonist. There is a one-sided crush, but the heroine never falls for him. The real male lead won't properly appear until much, much later, and even then, he'll barely be there!
2. This is a mystery and suspense story that turns various melodramatic tropes on their heads: swapped marriages, fake rich families, legitimate and illegitimate children, and the whole doted-on-by-everyone, mind-reading routine...
3. I usually write strong heroines, the really smart kind. There are strong male characters too. The seemingly delicate, innocent characters in this story aren't truly delicate and innocent. They're only weak because that's what they let you see. Most of them take a playful, carefree attitude toward life.
Theme: Good deeds are rewarded.