Because you are the best, the most consoling, the most sisterly of beings.
Why could he not be content with the sisterly regard she had ever felt toward him?
There was no question of kissing or in any way sealing her sisterly devotion.
It had such a sisterly sound coming from this sweet creature.
That makes her grin a little, and she pats my hand kind of sisterly like.
The rejection of him as a lover rendered the sisterly attitude impossible.
She could be sisterly to him over this without suggesting to him what she could not be to him.
And with a sisterly embrace they sought their private apartments.
"And Peace is to whistle," put in the small cherub with sisterly loyalty.
She moved up in a sisterly way to him and looked into his face.