Ninurta keeping Rana safe so he could take her to Cal, who could treat her. This stops him from taking his own life and facing his father.
In Chapter 120, Ninurta confronts his father in front of everyone in order to plead for his mother's life, who in turn does the same for him.
Really, most of Chapter 121 which shows their relationship growing up. They became utterly devoted to one another, which is surprising given she knew he wasn't really her son. She simply loved him that much.
Chapter 133, Nex and Depore reuniting after having been separated. Considering how he'd been up to that point, it's a stark change.