I watched the last 20 minutes of Spy Kids: All the Time in the World on TV and boy it is dark. Oh, spoiler alert, if anyone cares about the story in Spy Kids 4.
The villain's (named Timekeeper, I think) backstory is that he is frozen in time in a laboratory accident as a boy and watches his father work himself to death trying to unfreeze him. He is unfrozen when some people found some kind of sapphire from outer space that disables the time machine, but by then he is a traumatized adult mind in a kid's body. He wants to go back in time and unfreeze himself to save his father, so he becomes a supervillain who makes all sorts of time machine. It is revealed at the end that all of his minions are his future alternate-selves who went back in time after they all failed to save his father to help their past self to succeed. He succeeds going back to the past, but his older self returns to the present seconds later, I think after his father dies (spoiler: everybody dies) to tell the spy kids that being fixated on the past is pointless and that we should live for the future. Note that he is a very old man at this point. He is saying that his entire time-looped life has been pointless. The spies arrested one of his future selves who went mad and the spy baby beats his ass.
This makes me feel sad.
Have you ever seen anything like this in a book/movie/game/etc, where some parts of it is incredibly dark while the rest of it is incredible shitty family-friendly bullshit?