This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Hotel Transylvania
"Dad, can you do me a favor?" "Yes, of course darling, anything." "Will you erase my mind?"
Even more horrible for Drac, knowing that he actually can.
Him reading Martha's gift to Mavis also gets you.
And this utterly heartwrenching exchange:
Mavis: I thought we zinged, Dad.
Dracula: [surprised] You and Johnny?
Mavis: I guess it was only me. But you should be happy, Dad. There's no reason for me to leave. I have no more dreams. I'm just like you now.
The backstory that reveals Drac's wife, Martha, was killed by humans. You can finally understand just why he hates humans so much and all the secrecy and overprotectiveness he has towards his daughter.
Dracula: The legend is wrong.
After telling Johnny that he's "one of the good ones" and Johnny says that people have changed in the 118 years since Martha's death, Drac asks if he's absolutely sure about that. Johnny can't answer that, and he knows it, so he just stands there in silence.
Jonathan lying to Mavis about how he doesn't want to be with her and that he hates monsters. The look on her face just screams heartbreaking.