Chroniko's Death was foreshadowed the moment she made her first appearance. She wears a lamb hat, and her memories were released from her body, in short she was a Sacrificial Lamb.
Popo's Villainous Breakdown after losing his mother's memories near the end of the series makes sense when you realize that he spent most of his life hating her for something that wasn't her fault, and the moment he finally got her memories back, they were permanently taken away from him. Why? Because he lost the only chance he had to apologize to his Mother. Double Fridge Brilliance kicks in when it all comes together. Popo lost his mother once and because of his actions, he's lost her permanently; of course he went insane. He knew that everything he had done was All for Nothing. In short, he was punished for playing God.
