When David McLaughlin dresses in a pricey Darth Vader costume for charity, he can get overheated. And posing for photos with strangers can be tiring.

So when he feels like he wants to quit, McLaughlin thinks of a teenager he met five years ago at the Philadelphia Zoo.

There for an autism awareness event, McLaughlin remembers an "almost blind" boy who reached up and touched his Darth Vader mask.

"The look in his eyes when he did it," McLaughlin said, "that one little, three-second interaction locked me into this thing forever."

McLaughlin, 47, of Sellersville, is on the "command staff" of Garrison Carida, the eastern and central Pennsylvania chapter of the 501st Legion, a 10,000-member international volunteer organization also known as "Vader's Fist." Originally founded for Star Wars costuming enthusiasts, the group's mission is to use their screen-accurate get-ups to improve the lives of the less fortunate in their local communities.

Founded 15 years ago, the Garrison Carida chapter has about 165 active members who portray Dark Side characters like Darth Vader and the Stormtroopers with the motto: "bad guys doing good." The local group partners with nonprofits like Make-A-Wish Foundation and Toys For Tots, along with various regional children's hospitals, to collect toys, meet kids, and pose for a whole bunch of photos at about 200 events per year.

Organizers also line up a slate of events when new films drop. That means beginning Thursday and going through this weekend, when Star Wars: The Last Jedi hits theaters, Garrison Carida will have costumed volunteers stationed across the region, from Harrisburg to Reading to Collegeville.

The 501st Legion, known as Lucasfilm's "preferred imperial costuming group," doesn't charge for appearances and doesn't solicit cash donations. Instead, the organization encourages supporters to donate to other nonprofits in its name. In 2016, the 501st Legion raised nearly $900,000 for charity and contributed some 180,000 volunteer hours.

Jason Romanoff, a 44-year fraud investigator who lives in Delaware County, is the commanding officer and a cofounder of Garrison Carida. He saw the original Star Wars as a child when it was released in 1977, and he remembers watching the Imperial shuttle float across the screen. Smoke billowed out, and he saw Stormtroopers and Darth Vader emerge.

"It was just visually so powerful," Romanoff recalled. "I was like 'I wanna be one of those guys when I grow up.'"

Since he started costuming nearly two decades ago, Romanoff — a superfan who met George Lucas in 2010 — has cycled through 15 costumes that have cost from a few hundred to more than a thousand dollars each. Today, his "main" costume is his favorite: a Stormtrooper outfit that took months to build.

Romanoff loves the Stormtrooper's iconic nature. And, he admits, wearing a helmet can be strategic when visiting children's hospitals on a regular basis — it can cover up tears.

"I can well up at a child literally in a mesh burn unit, where he's in a chamber to keep him germ-free, to a boy who's just a recent amputee and is learning physical therapy," Romanoff said. "It makes you know how good you have things."

So why dress as the bad guys? Simple, McLaughlin explained: "Darth Vader gets more hugs than Luke Skywalker from the kids. He's cooler."

Romanoff often quips that it's because "dental benefits are really good on the Death Star." For the commanding officer, though, the magic of Star Wars has just always been with the villains.

"To have an intimidating Darth Vader get a hug from a little, ailing girl," Romanoff said, "that's a pretty powerful experience to be able to witness."