Accidental Aesop: One of the contributors to the Epilogues mentioned on Twitter that she takes issue with the common fan takeaway of "if you like happy endings, fuck you" from the work. The intended message was more along the lines of "things will never be finished or perfect, and disaster could always strike, but you can always bounce back."
Catharsis Factor: Ultimate Dirk Strider being almost silenced by Alt!Calliope in chapter 27 of the Meat route can be very satisfying to see.
Contested Sequel: The Epilogues, by themselves, are the most controversial thing Andrew Hussie has ever made. On one hand, some fans consider them very subversive on narratives and how canonicity truly affects a story. On the other hand, some believe that the Epilogues are a bunch of dribble focusing too hard on waxing philosophical views on narrative tools to really tell a good story or explore its characters. It also certainly does not help that they came out after three whole years of no Homestuck content (except Hiveswap). Their release certainly disappointed a great deal of fans, who expected a clean wrap up for the comic, only to be met with another story that, depending on the viewer, expands the story greatly or completely butchers it.
Epileptic Trees: Who, if anyone, is responsible for narrating the events of Candy? Theories include Alternate Calliope, dispassively narrating what happens inside her event horizon; regular Calliope from Meat, doodling on their bedroom walls; John, indirectly or unknowingly through his nihilistic solipsism; the fictional Andrew Hussie; Barack Obama; or nobody at all.
Evil Is Cool: Meat Dirk Strider effortlessly manipulates the whole cast and the reader while committing heinous deeds such as brainwashing Rose, incapacitating Jade, and indirectly murdering John, and he looks damn cool pulling it off.
Fanon: Roxy's sunglasses in the Meat route were never described as heart-shaped, but fan art universally depicts them that way. This was later canonized in Homestuck: Beyond Canon.
Fanon Discontinuity: In an unusual example, this was invited by the creators, as part of the "fanfiction" framing of the Epilogues and lengthy discussions on whether "canon" actually means anything. The authors have stated that readers inherently make their own canon and are free to disregard the Epilogues. How successful this invitation is is up for debate, especially since the Epilogues are necessary to engage with the fandom or understand Homestuck: Beyond Canon.
After Dirk made a second plan that relied on his own decapitation in Homestuck's final battle, it became a fandom meme that Dirk would approach any and all conflicts by saying "there's no other way out of this, you'll have to decapitate me." This became an Ascended Meme in Meat which both Dirk and Dave thought was hilarious. In Candy, however, Dirk decapitates himself for good in a decidedly not funny way.
Back in Homestuck, Dirk's Bro used his movies to make criticism of their in-universe government, with Betty Crocker (the Condesce) as the target. Dirk eventually reveals himself to be the narrator of a story that makes criticism of real-life government, with another Crocker at the center of it all. For extra harshness points, instead of being seen as a rebel like his Bro was, he's also one of the villains.
"do it for obama" and "think of the economy," two hilarious Dave lines with a surprising number of applications.
For those who saw the Epilogues as actively malicious toward the readers, the following lines from Aradia quickly became exploitable:
Aradia: you werent even sympathetic to the very story it seemed you were trying to get me invested in from the beginning
Aradia: almost like a mean prank!
Misblamed: One of Andrew Hussie's two coauthors, Jennifer "Cephied_Variable" Giesbrecht, frequently mentions her love of Homestuck's community. The other, "V", is more antagonistic. Due to this and the Epilogues' polarizing nature, some fans credited the parts they liked to Giesbrecht and blamed the parts they didn't like on V, regardless of evidence. Giesbrecht eventually made a Twitter thread asking people to please knock this off.
No Yay: Dirk's brainwashing and kidnapping of Rose. One of the most talked about plot points of the story and among the biggest deal-breakers for many fans.
Shipping Bed Death: Jake/Jane was never the most popular ship, but the utterly horrifying circumstances in which it finally sailed more or less caused its crew to rush for the lifeboats.
They Wasted a Perfectly Good Character: A common criticism of the Epilogues, even among fans, is that the women consistently play second fiddle to the men.
In the fight against Lord English, Rose, Jade, and Vriska are all taken out immediately. The actual fighting is left entirely to the boys (and Davepeta).
As a far cry from the headstrong and independent person she was in Homestuck, Roxy in the Candy timeline is completely submissive to everyone else's desires, passively supports Jane's genocidal regime, and never expresses any wishes of her own besides "being a perfect wife and mother" until near the end. And while their/his transition in Meat outwardly presents a more active narrative presence, Roxy is still entirely neutral in a conflict which could affect millions of lives and could be swayed by their/his actions.
Jade is relegated almost exclusively to a plot device, existing to complicate Dave and Karkat's relationship in Candy and spending the entirety of Meat as an unconscious vessel.
Calliope only gets a handful of lines, and her/their sole contribution to the plot is asking John to bring Gamzee back in Candy, which was an overwhelmingly negative thing.
Too Bleak, Stopped Caring: Chapters 12 through 27 of Candy are a long, near-joyless slog where the characters' long-standing friendships dissolve and their happy ending is violently ripped away, and what few happy moments there are deliberately so fake and artificial that they only make things feel worse. Things finally start picking up in chapter 28, heralded by Vriska Serket's return.
Unexpected Character: Though it was foreshadowed by his inclusion in the list of characters (which some thought was a joke), almost nobody expected President Barack Obama to show up, much less in the manner he did: a holographic, Ambiguously Gay, ascended Hope player who helps Dave realize his destiny.
that she takes issue with the common fan takeaway of "if you like happy endings, fuck you" from the work. The intended message was more along the lines of "things will never be finished or perfect, and disaster could always strike, but you can always bounce back."