My 6-year-old has tantrums only around his grandparents. He's pushing his independence with people he knows will comfort him always.

• As a first-grader, my son suddenly began having tantrums — but only when he was with my parents.
• I felt disconnected from my child because I didn't understand how to help.

During my son's first-grade year, when he spent time with my parents, his personality changed. I've watched him morph into a tiny version of Mr. Hyde: short-tempered and snarky, throwing shade and Legos.

As he was typically a sensitive and thoughtful kid, his sudden moves to the dark side baffled me. There were no major meltdowns at home or at school, so what was it that made time with grandparents so special?

"Hey, kiddo, two more hide-and-seeks and then Grandpa will be finished," I reminded him.

"Noooooooooooooo," my son not so subtly replied.

I'd given many warnings that Hide-the-Grandpa was coming to a close, but my kid was not pleased, and he let me know this with some majorly misplaced sass, complete with stomping. I dusted off my terrible-twos meltdown list to see if I could find the cause. Was he hungry? Nope. Was he overtired? Also no.

When he loudly declared, "Kiss my boo-boo butt!" I felt a sense of mild shock, as if I'd caught a glimpse of teenage comebacks to come — until the following meltdown, when he regressed to a puddle of toddlerlike goo on the floor.

What works at home didn't work with his grandparents

The next tantrum happened because I'd informed my son that dessert didn't come before dinner. We have a dessert-after-dinner rule at our home that works fine — but this didn't apply when he was with my parents.

Watching my child lie like a slug on the floor mumbling something about death and doughnuts made my stomach rumble, but not because I was hungry. This is how it'd been going down with my parents for many months, and I felt disconnected from my kiddo. Without a deeper understanding of these outbursts, I felt powerless to help.

I'm not a total newbie to my son's experiencing a big emotional moment. When my little one was a "threenager" and cried because he preferred to skip bath time and spend the night covered in pizza, there was a simplicity behind his emotional release. His tantrum was a direct result of his disappointment.

This time around, the meltdowns seemed to be an extension of something more complex — I struggled to understand what that was.

He's between a big kid and a toddler

First grade has my kid taking his first steps into the land of the big kids. I've watched him vacillate between a new, empowering autonomy and a familiar interdependence. Some days he's asked me to help put on his shoes, and other days I've heard a decisive "Mom, I can do it!"

For the past six years I've been the boss of my son, and now he's learning to be the boss of himself.

And then it hit me like the tiny flying Lego piece had earlier: Where's the safest place to express all of this pent-up independent-kid angst? With his grandparents.

Consequences with Grandma and Grandpa are few, and the love is great. The support my parents offer has been a source of refuge for him his whole life. He feels safe pushing the envelope of his autonomy, knowing instinctively that there's no way he can push too far, to a place of rejection.

After spending the day with his grandparents and working through some big emotional moments, before climbing into bed, my son whispered, "Mom, let's read this." He must have been craving the familiar, because he handed me a picture book from his toddler days. I could've recited this 12-page tome without opening the cover — but my 6-year-old wanted to read it to me.

Snuggling together, I finally figured it out: My son needed a balance between the familiar and the unknown. As he explores this newer side of his personality, these moments would ease us through this phase — and move us on to the next.