At the end of chapter 7, what reinforces for the reader, that despite all that has happened to him, Oliver remains inncoent and good?

I suppose that despite Sowerberry beating Oliver and locking him up, Oliver still retains his sense of innocence. Oliver's rage is only temporary and as he runs away, we don't get a sense of retribution in his heart. On his way out of town he still finds it in his heart to stop by the workhouse and say goodbye to his old companion Dick.