Mother's speech to Schofield that prevents him from committing suicide after Gant's death.
Five Greatest Warriors
West's discovery of the tomb of Jesus Christ. He refuses to look at the man's face, considering himself unworthy.
The Great Zoo of China
This one actually has quite a heartwarming moment in the post-book interview, with Reilly's offhand mention of his girlfriend. After the tragic death of his wife a few years earlier and the Creator Breakdown it sent him into, it's great to see he's getting his life back together. The book also sees his writing back at the same level of sheer fun he started with, after the Darker and Edgier couple books before it.
The Four Legendary Kingdoms
Jack saves a trapped minotaur from certain death, something that literally has never happened in the history of the games.
After being forced to kill Scarecrow in a fight to the death that Scarecrow agreed to throw, Jack rushes to save his life after the climax. It works.
Rather than kill Hades for running the Games and costing dozens of people their lives, Jack offers his hand in friendship and gains a valuable and powerful ally for the upcoming trials.