When my older son Alex was a child, he did everything before he knew how and without considering if it would work. He walked and fell, rode a bike and crashed. He tried to be a grown-up his way. He crashed, he burned, he learned.

When my younger son Nicolas was a child, he didn’t do anything until he knew he could do it without fail. He waited until he was 16 months old to walk, and one day, he stood up and ran. He read when he could understand complete sentences. After many difficult bike riding lessons with his father, he couldn’t do more than one or two pedals before falling. Then one day when his father was facing the other way, Nicolas took off down the street.

Alex is an anarchist. He is a hater of leaders and laws, a college graduate and now writer who envisions a government as slim as a piece of paper. He despises anything that enforce rules on the masses — traffic signs, tax laws, social norms and customs.

Nicolas, on the other hand, is a military history major, a college graduate, a police academy aspirant and law abiding citizen with one moving violation that he erased through traffic school.

At one time, these were my happy little boys, my sons who played together all day on the weekends, slept in the same room for years. In that small bedroom, they had an enormous Lego town, a town that stayed together through two moves, only dismantled when Nicolas was a sophomore in high school. When they played with the town, Alex took charge, taking the role of the main character, Nicholas was everyone else.

They both went to the same college, called each other frequently, hiked together, laughed together. But when Nicolas began to become the man he is, their ideologies started to pull them apart.

Nicolas could no longer go to the rallies, the protests, the angry mob scenes at the United States Army base in Tacoma. He couldn’t listen to Alex’s wild tales of anarchist revelry. He began to despise all that Alex stood for, and their drives home from Washington State for visits began to get ugly, full of silences or harsh words. When Alex found out that Nicolas was applying to police departments for work, he felt his brother was attacking his principles.

Our last meal together, all of us sitting around the table of our new home, was as unpleasant as could be.

“Could you just stop?” Nicolas yelled, putting down his fork. “I can’t listen to this propaganda anymore. You’re just lazy. You just don’t want to work.”

“And you’re doing this cop crap to spite me,” Alex shouted back. “You don’t really want to be a pig, do you?”

“You think my choice is about you?” Nicolas said. “How narcissistic can you get?”

Finally, after more emotional punching, Nicolas pushed away from the table. Alex followed him in to the kitchen, words flying like missiles, despite my attempts to break up the fight. I eventually managed to quell that argument, but all throughout their visit here, the fight erupted again and again, ending with a tense, silent ride up to the Northwest and a standoff that lasted for months.

I have a photo on my desk of my two curly-headed boys, Nicolas hugging Alex, Alex’s arm pulling him close. Both are smiling big-toothed smiles. But these two little boys are gone. And the little brother doesn’t want to be the tag-along anymore. He’s his own man, with his own values and his own life, and what he wants is his brother to accept him. What Alex wants is for the little brother to be that brother still. Who wouldn’t? Who wouldn’t want to be adored and idolized? Who would want to watch that powerful role of the older sibling diminish?

Used to this adoring role but trapped by it, Nicolas fights back, wanting his ideas to be heard, his life to be the focus, for once, for now. Seeing that the past is slipping away, Alex holds on, too tight, too hard.

I also want to cling to that long-ago brother relationship because it was magical. Somehow, I thought back then, I did something right with these two.

The fighting. This is the part of parenting that we don’t think about when children are in diapers. Here is when children become adults, and adults don’t always agree and then happily eat peanut butter-and-jelly sandwiches together. Adults learn how to individuate, and that’s what I’m watching now.

It’s possible that these two will never come back to one another. This fight could be the axe that splits their relationship wide open, breaking it forever. I close my eyes and breathe in hard when I think of them forever at opposite ends of things. Our siblings are the people closest to us in time and age and place. Our siblings know us in ways no one else can, and to see my boys get close to losing this connection is often more than I can bear.

Though it’s possible things may never be repaired and despite the fact that their evolving relationship is painful to watch for all three of us, I have faith that under everything is that hug, those smiles, those two boys in the photo taken so long ago.

Jessica Barksdale poetry collection “Grim Honey” is forthcoming in April. “The Play’s the Thing,” her time-travel Shakespearean romp, will be published in May.