YMMV / Some Things Never Change

• Accidental Aesop: Never assume that your past can't catch up with you. Both Mr. Krabs and Squilliam assumed themselves to be untouchable, only for their crimes to be revealed in the worst ways possible and, of course, lands them both in this universe's version of Hell.
• Harsher in Hindsight: SpongeBob’s obliviousness to reality and childishly optimistic outlook, which provided a lot of the humor in the first and second story, become this in the third, when it’s revealed he’s actually been in willful denial all this time as a coping mechanism to deal with all the personal tragedies he’s experienced over the years, like his grandma and personal heroes passing away from old age. Fridge Horror also sets in, once you realize that he was likely aware of how Sandy and Mr. Krabs were trying to shelter him and played along to further keep himself in his comfort bubble, to the point that he truly believed (to a certain extent) that his world was operating on Comic-Book Time and Status Quo Is God.
• Jerkass Woobie: Squidward is already this in canon, but both fics really hammer in just how miserable his life has been and how much he has squandered it in his obsessive but futile pursuit of fame and recognition. Even him learning to move on at the end barely qualifies as a Bittersweet Ending.
• MST3K Mantra: How does the Fountain of Youth exist at the bottom of the ocean? Because it's SpongeBob SquarePants.