After dinner, the kid wanted a treat. He had been looking forward to it the whole time. The dad explained that the kid could not have any sugar based on behavior last time the child had sugar. The child threw a tantrum and was very upset with the dad.
Leaving the kid with his mom, the dad went to run an errand. While the dad was gone the mom, feeling frustrated with the tantrum throwing child told the kid he could have a treat if he went inside and asked for it. That if got over his shyness of strangers and earned the candy she would justify him having it.
What I saw was the mom showing the child that whatever dad said would be second to what the mom said. That if the child was enough of a pain in the ass, he could convince mom to give in. The kid had the candy and was an even bigger pain in the ass.
Because of sugar,
because he beat dad.
Dad has no authority. Mom has no authority. The kid is a bully.