Character who achieves Atonement

Atonement is said to be the the process of forgiving or pardoning a transgression. I dont think any of the characters achieved atonement. I think Briony is trying to achieve it but her sister won't meet up with her. She has the most to apologize for since she is the reason Robbie and Cecilia were seperated in the first place. I know that Robbie would of probably been sent off to war anyways, but she humiliated him in front of her family. Briony is the one of the biggest reasons why Cecilia won't see her parents. In Briony's fictional story she kind of gets atonement by Robbie and Cecilia but it is fictional. The truth is no one achieves atonement in the story.