Etta follows Tye everywhere. When Etta is in the carrier and Tye runs ahead, Etta yells at her and reaches her hand out towards her. When Tye puts on her snorkel mask in the bathtub and blows bubbles under water, Etta blows raspberries on top of the water. When Tye offers Etta a bite of food, Etta eats it. Period.
Before bed each night, the girls say goodnight to each other. I might ask one or the other if they want to say goodnight, but then, on their own, they hug and kiss each other before they walk to their beds. Even if naps fail and Etta is up late, she still won't fall asleep without waving towards Tye's bed, saying, "Niiiiigh!" and blowing her a kiss.
No matter how roughly my day is going, when I think about the girls' relationship with each other, I can be confident that I actually am doing something right.