@annamorgause :
Took me a while of back reading to find out relevant stuffs.
What happen in this chapter seem to be relate back to the 3rd test (with the giant dog monster) where before the fight she prayed to goddess Fraya.
Her wish was for her to live a long and healthy life, whether as a Visenna or a maid, and that she'd donate her money/cookies to the church if her wish was granted, and it seem she took the dad's intervention as a sort of her wish being granted so she's going to give him her cookie since he protected her.
The brother then 'sulk' a little since he's the only one who hasn't gotten a cookie from her, hinting that the brother is aware of her little chat with the grand duke before the 3rd test (where she gave him half a cookie, and now the dad)