When Bast gives a loving goodbye to Carter in the beginning of The Throne of Fire. Carter is moved by the affection she shows for him, because in the past he always thought of Bast as only Sadie's protector, and himself as just an extra burden for her.
Also, in The Red Pyramid when she swears never to leave their side again.
"You two are like kittens to me now."
Sadie restoring Bes, who then gets together with Tawaret.
Carter finally getting to take Zia on that date at the mall.
Sadie accepting that she can have both Walt and Anubis and not lose either because of a curse or be separated forever by the god of air.
The cat-goddess Mekhit purring as she slow dances with her long lost husband.
All the little moments where Sadie and Carter understand each other for once, especially when Sadie learns Carter's secret name and doesn't tease him for once.