I am a sucker for "Earn Your Happiness" tropes -- wherepeople who actually have character development end up overcoming the pain they endured in the story (or at least begin to), and they're definitely at a better place at the end.
I know this is often used for romance (where two characters who mutually love each other end up together), and I love that too. But often, for me, it's when the parent who was spending the whole story saving their kid ends up seeing them safe and sound and just rushes to hug them and cries it out.