For me, it was definitely when Kratos is speaking to Mimir to warn Mimir about seeking vengeance. Mimir snaps at him, saying of all people, you're one to talk! And Kratos replies:
“I am an authority on the subject. You would do well to listen."
Honestly, this interaction impacted my perception of people and when they have insight that is counter to their behavior.
I also found the "Do Not Mistake My Silence For Lack Of Grief." Quote very fitting. Just because you are not showing it doesn't mean it doesn't affect you.