Approaching difficult topics in D&D

A while back when my kids were younger (7 and 9 years old), we were playing D&D with my sister, brother-in-law and a friend. Their characters had just battled some orcs and were making their way back to town and came across a man and woman with two kids being attacked by goblins. 

After they defeated the pesky goblins, the characters decided to hang out with the 'family' by the fire. As they were telling stories of what they had been up to, the father told one of the kids to serve him drink. The father became increasingly abusive since the kid was taking too long, and then things escalated when the kid spilled one of the drinks.

As the DM, I wanted to gradually increase the verbal abuse to see what my own kids would do. Surprisingly, they did not defend the kids, and my brother-in-laws's character ended up getting involved. After the fight, they would find out that the kids were slaves taken from their family due to a debt.

I asked my kids why they did not say something to the father that had become abusive and they told me that they were unsure what they could do. This perplexed me when I heard it, since they never held back when dealing with unruly orcs or goblins. From further discussion, it appeared that they were being held back because the father was an adult and they defaulted back to being kids instead of their characters.

This is one of the benefits of D&D. We can play through uncomfortable situations within a safe environment. Even though my kids didn't take the initiative to stop the abuse, they were quick to attack once their uncle stepped in. This allowed me to start a conversation with them concerning abuse from adults.