Since I'm not going to be continuing the story myself, I'll tell you what was originally going to happen had I did.
The main reason Arthur Puppington was willing to make amends with Clay was because he was dying of cancer and wanted to clear the air with certain people before passing on. Some time before, Arthur had begun seeing Mr. Claymore to help deal with the terminal illness emotionally. William suggested Arthur to clear the air with his son during the therapy sessions as an act of catharsis. Unfortunately before he gets a chance to have a heart-to-heart talk with Clay, Arthur dies in his sleep.
They had a funeral service for Arthur as