Daniel Radcliffe schmoozes with the audience in sweet one-man show

It’s safe to say that Daniel Radcliffe has outgrown Harry Potter. On Broadway, most of all.

The British boy-wizard-turned-man-thespian has starred in six shows over nearly 20 years in parts as divergent as a troubled teen who stabs horses and a power-hungry singing businessman. Tony-winning Radcliffe takes risks, and gets better and better for it.  

But in the warm one-man play “Every Brilliant Thing,” which opened Thursday night at the Hudson Theatre after hundreds of stagings around the globe, the gifted actor’s distant Potter past comes back to haunt him. In a good way! For the first time, I felt him running toward Hogwarts, not away from it.

During the aughts, Radcliffe was synonymous with Harry, the fictional wand-wielder hundreds of millions of people grew up with and profoundly related to; an orphaned student who endured a traumatic childhood, battled demons (sometimes literal ones) and still ended every film and book with an attitude of hope.

Now at the Hudson, the actor begins as a different youngster faced with hardship. Yet we feel, in a deeply empathetic sense, as if we already know him.

After his mom attempts suicide, an innocent 7-year-old decides to make her a list of the world’s wonders (less the Hanging Gardens of Babylon, more “ice cream” and “Christopher Walken’s hair”). He wants to do something to help, so he becomes the boy who lived life to the fullest.

As the narrator ages, finds love and experiences heartbreak and loss, the list explodes to contain hundreds of thousands of items and evolves to be just as much for him as it is for her.

The natural qualities that made Radcliffe a perfect Harry echo in the unnamed main character in Duncan Macmillan’s 2013 mental-health play: his excitable geekiness, comforting aura and palpable interest in other people.

That’s a relief because the audience is his only co-star.

Before the lights go down, an older, bearded Radcliffe mingles with the crowd as they file in from the street into the theater that has been resituated intimately in the round, and he hands out assignments.

Nobody shrieked or froze up when confronted by the star, from what I could tell. Their faces betrayed a fuzzy happiness, like a surprise run-in with an old friend. And in a roundabout way, he is one.

Radcliffe, bouncing off the walls, gives ticket-buyers numbered index cards to read (each one has a brilliant thing written on it) or roles to play: his quiet father, a child therapist who turns her sock into a puppet and his college boyfriend, Sam.

The chosen few are forced to improvise a little. And on the night I attended, they all had a flair for the dramatic. A tad too much flair, really. One chosen participant had 432,000 Instagram followers. The play’s charms best come through with unassuming players who only know “Method” as a brand of cleaning products.

The ones clutching paper have an easier job. When prompted, they shout their “thing” when Radcliffe calls out their number. Sounds come at you from all directions.

If, like me, you do not include audience participation on your personal list of brilliant things, know that it’s all voluntary.

The play, directed by Macmillan and Jeremy Herrin, is brisk — about 80 minutes — and always affable. Although I can’t say I was bowled over by anything but the leading man.

Since its star-is-born run at the Edinburgh Fringe Festival in 2014 and winding up off-Broadway that same year, “Every Brilliant Thing” has grown a bit dated and, frankly, quaint. Social media and the internet don’t play a role, for instance, when they are enormously relevant to the mental health conversation.

And the show’s tone sometimes brings to mind the old positive-thinking craze, a la Shonda Rhimes’ “Year of Yes.” Its humor can lean hokey as well, but that’s forgivable. This is aiming to be uplifting — not “Oh, Mary!”

It’s Radcliffe’s vitalizing and vulnerable performance, a cardio workout both physically and emotionally, that’s the reason to go. He’s its most brilliant thing.