I took my grandson to lunch with my sons Ex-Wife without his knowledge or permission
Is there a reason to hide that from your son?
My son pissed me off and my grandson asked me to take her.
It is not nice to meet behind your son's back. Let him know next time.
I don't care about my son's problems. I want to make my grandson happy, and if that troubles my son, then he should grow up.
You should care about the well being of your son and your grandson. Don't do things you know will upset them.