How to make small talk with your colleague's family, whom you've only met because he's lying in the ICU swathed in bandages and connected to dozens of tubes. How long it's appropriate to stay in the waiting room with them. What to say after asking how he is, after asking them how they are, after offering to cook things for them to eat & help them get anything they need, after delivering the cards the kids made, after telling them how he was/is becoming a great teacher. How to tell how long is appropriate to stay. How to determine whether they have so many visitors it is overwhelming, or whether they feel better seeing you. What to say when you see him for the first time, still unconscious but possibly able to hear.
Everyone makes up this stuff as they go along, I guess. I think we are doing an all right job of it, but man.