I was just about to post the same thing.

To the OP, the Foreigner series is long (9 books now, I think) and is literally all about character and character development over several years. Even the series title is a reference to the psychology of the main character.

CJ Cherryh has a very particular writing style and not everyone relates to it, but she's one of my favourite authors and I think this is her best series. I highly recommend giving it a try, at least checking out the first book. If you like it, there's lots of great reading awaiting you afterwards.