No spoilers have been marked! You have been warned.
Wirt's semi-disregard for Greg for half the series might be cringe-inducing for anyone who has a sibling.
It hits especially close to home for anyone with a huge age gap between them and their sibling.
Wirt's reaction to Beatrice's betrayal, especially since it was coerced and she was about to go back on it anyway when he found out. He's driven so far into despair by this that he becomes prey for the Beast, which causes Greg to make a Deal with the Devil to save him. His reaction when he finds out about that is also heartbreaking.
After Greg realizes that there's no hope for his brother, he makes the selfless decision to give himself up to the Beast in his place. It's Greg's defining moment as a character and is incredibly heartbreaking.
Wirt frantically yelling and searching for Greg when he realizes that he's gone, leading to him falling through thin ice (although he's saved by the fish that had been fishing earlier in the chapter) and losing consciousness. The desperation in his voice as he's looking for Greg really shows Wirt's Character Development and how much Wirt's grown to care about Greg's safety.
The perspective we get on Wirt's insecurities is really funny and really sad. Wirt's paranoia about Greg and his stepdad persecuting him and his increasingly panicked attempts to get back the tape without having to actually talk to his classmates are hilarious, but even if his anxieties are ridiculous they're real to him. The other teens obviously care about him and consider him a friend, but he thinks they don't even want him around.
"You'll be no good to your brother dead." "I was never any good to him alive, either."
Greg falling prey to the Beast and nearly freezing to death, all while maintaining his enthusiasm despite audibly getting weaker, is extremely hard to watch. The somber reprise of Potatoes and Molasses that plays when Wirt finally comes across Greg does not help one bit either. And the fact that Greg requests Wirt return the rock he had stolen from a neighbor indicates that he has grown a sense of mortality and believes he won't be around anymore.
From the same scene, Wirt finally breaking down and apologizing for treating Greg poorly and getting them lost. He even has to be the one to give Greg the will to keep going.
The somber, Latin reprise of "Potatoes and Molasses" when Wirt finds Greg in the middle of turning into an edelwood tree is followed by a single line from "Come, Wayward Souls."
Grow, tiny seed. You are called to the trees.
The sheer horror in the Woodsman's voice when he realizes the truth of how edelwood is made.
The Beast: You've been grinding lost souls for years. The Woodsman:I didn't know! I didn't know this is where the edelwood comes from! The Beast: And would it have mattered?
After this, the Beast tries to guilt the Woodsman for "not caring for his daughter anymore". The Woodsman's response is equal parts awesome, heartwarming and tragic.
The Woodsman: HOLD YOUR TONGUE OR I'LL REMOVE IT FROM YOUR MOUTH! And do not speak of my daughter. She wouldn't have wished this.
The Woodsman's whole situation, but especially when he realizes that his daughter's soul was never in the lantern to begin with.
"You'll never see your daughter again, woodsman! Are you really ready to go back to that empty house?"
Wirt and Beatrice's goodbye, which isn't shown onscreen, but can be overheard as the previous scene fades to black.
It's also sad as we are also saying goodbye to the characters we have fallen in love with. It's a powerful ending to one of the best Cartoon Network cartoons of all time.
It's barely mentioned during the series itself, but Wirt and Greg are half-brothers (Wirt mentions that his mom "gave birth to [Greg] after marrying [his] step-dad"). This leads to two possibilities: Wirt's biological parents are divorced, or his biological father has passed away. Either one is pretty sad, especially when you consider how much Wirt resented his step-father (and by extension, Greg).
The theme song, "Into The Unknown", can tug at the heartstrings.
How the gentle wind,
Beckons through the leaves,
As autumn colors fall.
Dancing in a swirl,
Of golden memories,
The loveliest lies of all,
The loveliest, lies of all.
Poor Mr. Endicott's greatest fear is that there is no ghost, and he's just going completely senile. Even with the happy ending, his age and overall demeanor give the impression that dementia really is a possibility. This makes Beatrice's plan to rob him while Greg and Wirt pretend to be his nephews particularly cringe-worthy — seniors with dementia and other mental problems that affect their memory are often targets for theft, especially from relatives and caretakers.
While the ending of the episode means that he now at least has Marguerite to keep him company and help take care of him, the epilogue shows her wistfully gazing at his portrait, implying he might have died not long after. Given their obvious age difference, it was inevitable, but still very sad.
takes that idea and runs with it.