Season 1

Any time Ron's childhood with Willie is mentioned.
When all the dads find the moms and the letters they left behind in the pyramid. Ron's letter is especially tear-jerking.
- Almost as bad is when some of the dads have to choose a spot to bury them and hold a small funeral.
Grant going through depression and trauma to the point of hurting himself and others just to feel something, and when he finally tries to talk to someone about it, it ends with Yeet rejecting him.
It's really hard to watch Glenn go through years of torture and solitude only to come back to a son that not only doesn't recognize him, but actively dislikes him.
Henry realizing that Lark hates him.
When we see a flashback of Ron having to give up his childhood dog, Anthony gets choked up and has to take a second to collect himself.
"It's okay to be angry. It's not okay to be cruel."

Season 2

Sparrow telling his son that he's embarrassed about who Normal is growing up to become.
Scary telling a spectral Terry Jr. to go away after he offers to leave for good after their ordeal is over.
Terry Jr.: This might be it. I hope I see you soon, or also I hope maybe I don't. Maybe you don't need to come to see me. I just want you to be safe. I want you to be happy. Tell your mother that I love her very much, and… I will stay out of your life for good.—
Scary: Yeah. So, y-y… go away, or...
Terry Jr.: Okay.
Anthony: And he fades away.
Scary: Or— F— Or... [quietly] fuck...fuck!
Episode 23 is full of these:
- The revelation that Lark is full of anger and self-loathing for essentially having ended the world and doomed the residents of the Forgotten Realms to A Fate Worse Than Death.
- The revelation that the Doodler is essentially a frightfully-powerful cosmic child that craves love and approval but can't help but accidentally hurt people as it tries to reach out to them.