Staring at my TV last week, I was half-watching a trailer for the Showtime show “Shameless” when I realized I was staring at my middle son’s face. The surrealness of the moment was heightened by the fact that in the ad, Darrell was wearing the stubborn, “Don’t mess with me” expression he adopted long before becoming a Hollywood actor; it first appeared when he was two and refused to do my bidding.

Darrell (Courtesy Donna Britt) Darrell (Courtesy Donna Britt)

I’d seen the look hundreds of times, but this time, it felt different. In that split-second, framed on a 37-inch screen, Darrell’s beloved features seemed chilling, suggesting things antithetical to what I knew about my son, but that viewers who’d never laid eyes on him could instantly perceive: The threatening scowl of a dangerous young black man.

We’ve all had moments when a turn of the head or trick of the light revealed something unexpected in a loved one’s visage. My son’s face on the trailer of the William H. Macy-starring dramedy flashed so briefly, no one could infer that he’s my funniest, quickest-witted, most metrosexual — how many straight guys rock pink sneakers? — kid. But even a second onscreen was long enough for his features to suggest a cold-hearted thug’s.

Most people would shrug and call what I saw “acting.” They’d say it’s no big deal, which I later could acknowledge myself. But in that split-second as Darrell’s mother, it felt almost tragic.

A dozen thoughts whipped through my mind: How handsome and powerful this glaring stranger looked; how grateful I am that my son is earning a living as an actor without waiting tables or parking cars. But mostly it was unsettling, seeing my multidimensional kid reduced — even momentarily — to a misleading stereotype. I recalled how for years I had underestimated the talent and smarts of gifted actors like Don Cheadle and Samuel L. Jackson back when all they seemed to do onscreen was to glower and threaten. Even saintly Morgan Freeman wasn’t exempt — before playing U.S. presidents and God, the actor channeled a brutal pimp so convincingly in “Street Smart,” it earned him his first Oscar nod. Few black actors triumph without paying some dues via forays into cinematic menace. Why would my son be different?

But so far, he mostly has been. Darrell has portrayed a clueless hoops player in a wireless company commercial, an earnest student for an automaker, a bespectacled nerd who voluntarily gets slapped by a robot in a snack ad, a candy-producing human vending machine and most recently, an eager basketball fan choosing players from a lineup of NBA stars. Each successive role has only made me prouder.

I’m cool with my son playing dim bulbs and human Pez dispensers because when it comes to stereotypes in 30-second ads, silly beats sinister for me any day. You see, life-and-death decisions can be made in split-seconds. And the overriding image plaguing black men in the Obama era isn’t that they’re dumb. It’s that they’re dangerous. And though I despise both stereotypes, assumptions that young brothers are dim can get them overlooked and disrespected. Assumptions that they’re dangerous can get them shot — as countless deaths like Trayvon Martin’s, the anniversary of which was marked last week, prove.

Admittedly, I minded such stereotyping a bit less five years ago, when Darrell got his first break playing a murderous enforcer for a Baltimore drug dealer on HBO’s “The Wire.” Back then, I felt pride in him as an emerging actor even as I despised his feigned criminality. But on that show as in real life, villains and good guys came in every color, and were so complex that from week to week, it was hard to tell who was which. In independent videos that Darrell writes and produces in Los Angeles with other younger actors and filmmakers, he enjoys playing lawyers, airline pilots, teachers, stockbrokers — roles as varied as those played by young black men in real life. As for his role on “Shameless,” playing a teen who without provocation goads another at a juvenile facility, a friend who loves the show — and who once was Darrell’s babysitter — watched the episode and felt nothing but pride.

“He was playing a bully, and bullies come in all colors,” she sensibly opined. “He’s an actor. Just be happy that he’s making money doing what he loves.”

I am happy. But I’m also a mom who knows how impactful split-second assumptions can be. So I can’t help wishing folks could see — even in a fleeting TV trailer — that no matter what his color, every young man has the complexity God gave us all.

Even when he’s acting.

Donna Britt is a former syndicated Washington Post columnist whose memoir, ‘Brothers (and me): A Memoir of Loving and Giving,’ was published last year.