[[folder: The first series: The 39 Clues ]]
* Amy and Natalie's brief conversation about mothers in book 9, ''Storm Warning''. Given that Amy's mom has been dead for seven years and Natalie's mom is [[spoiler: the BigBad of the series who is responsible for Amy's mother's death, and psychologically abuses her children to boot]], this makes for a scene that tugs at the heartstrings...especially when you see how loyal Natalie is to her mother, despite [[FridgeHorror (or because of)]] the abuse. And how caring and big-sisterly Amy behaves towards Natalie for a moment....
[[folder: The second series: Cahills vs. Vespers ]]
'''Warning''': Potentially unmarked spoilers for ''The 39 Clues''.
* In the third book, when Ian thinks to himself "For that to be the price of a family's happiness? Unimaginable. In fact, he couldn't imagine a happy family at all." Made even worse by the conversation he's just had with [[EvilMatriarch his mother]], who told him that she doesn't want anything to him or his sister, who's been kidnapped, and rubbed in his face the fact that most of the people at the [[CombatAndSupport Cahill Command Center]] barely put up with him.
* [[spoiler: Alistair's death]].
* Then, in ''Day of Doom'' (as if there hadn't already been enough depressing things up to this point), [[spoiler: Evan and Natalie's deaths, Ian crying over the body of his little sister, and then ''Isabel's'' reaction to Natalie's death--as well as the scene where Amy sees the spirits of Isabel and Natalie walking together, holding hands, happy.]] It's all very sad.