How we cite our quotes: All quotations are from Unforgiven.
Quote #1
WILL: I thought maybe you was someone come to kill me for something I'd done in the old days.
Will seems aware that his past may come back to bite him in the butt. His first thoughts of the Kid, here, prove as much. He knows there must be a ton of people who are determined to "fix" the past.
Quote #2
WILL: I used to be weak, and given to mistreating animals. This horse and them hogs over there are getting even with me for the cruelty I inflicted
The past eventually catches up to you, and Will seems to think this explains why he's having such a hard time with his hogs and horses. They're "getting even" with him, punishing him for what he used to be.
Quote #3
WILL: He didn't do anything to deserve to get shot. At least nothing I could remember when I sobered up.
From his vantage point in the film, Will seems legitimately disappointed with how he acted in the past. He realizes that he has done things that he shouldn't have done, which suggests he is feeling at least some regret.