When Sissi suddenly runs back and kisses David on the cheek as a "thank you" for all the help he's given her.
Paul and Marion drive a whole day just to see that David's doing okay. Obviously he's not okay at all and Paul has to save David from killing himself. Paul then has David tell him what's going on. And believes David instead of calling him crazy or anything else.
Sissi, D and Fluffy urging Paul to help David.
"He's your friend, right? Go to him."
When David finds where Duke killed himself, he suddenly realizes the reason for everything that happened. Duke lived a life very similar to David's. He tried to kill David because he hated how similar he was...and at the same time he also tried to save David because he didn't want David to come down the same path he did. David thanks Duke for helping him and ensures that Duke receives a proper burial so he can finally rest in peace.Sniffles.
David's mother being cured of her insanity long enough to enjoy the first happy moments with her son she's had in a long time. Sadly, she dies soon after, but she has no regrets.