I suppose Santa Clause is rather
“The wish of parents that they want their children to be the kind of kid who believes in Santa”.
So the duty of children is to grant them this wish.
In my family’s case, sometimes Lupin the third came from time to time
And left the letter that says
“Your money you got from Grandpa is in our hands
-Lupin the third”
The handwriting looked as neat as my mum’s.
