The foursome marked the second anniversary of the Boston Marathon bombings on Wednesday evening, meeting up for dinner at a restaurant in the city’s North End neighborhood.

The college kid, the firefighter, the police officer, and the real estate executive have made a habit out of keeping in touch over the past two years, texting, emailing, and hanging out for the heck of it.

“We’ll see each other more this time of year,” said the college kid, Shores Salter, a fifth-year chemistry student at Northeastern University. “It’s nice to be with them,” he added, “but it’s difficult because it brings back some tough emotions.”

Those emotions—fear and agony, sadness and anxiousness—date back to April 15, 2013, Boston’s darkest day.

Salter, S’15, and his college buddies had turned out to Boylston Street to celebrate the 117th running of the Boston Marathon, an annual tradition that had begun in their freshman year. The real estate executive, Roseann Sdoia, had been attending the race ever since childhood. An avid runner, she found a prime viewing spot behind a makeshift fence to watch the runners cross the Boylston Street finish line. The police officer, Shana Cottone, was working the finish line, a last-minute assignment switch with another officer that had asked to work the Boston Common with his carpool pal.

At 2:49 p.m. Salter and his friend were walking toward that legendary blue and yellow line—that indelible marker of pure athletic bliss—when they heard a loud boom. At first, Salter thought that it was the sound of celebratory cannons, fired in honor of the first finishers. “But then I thought that didn’t make sense,” he said. “The winners had finished three hours ago and I had never heard them let off cannons before.”

Moments later, he heard the second explosion and looked across the street to see smoke, blood, body parts. He hopped the guardrail and sprinted over there to see if he could help. “I don’t have a great answer for why I stopped and went toward the second bomb,” he said, noting that he and his friend had gotten separated amid the chaos. “It was fate.”

Salter then heard a woman yelling, calling for assistance. It was Sdoia, whose right leg had been badly injured. He picked her up and carried her into the center of the street. He removed his belt and turned it into a tourniquet to stanch the bleeding. He applied pressure and he waited for professional reinforcements to arrive—one minute, two…Cottone arrived, and tried making small talk with Sdoia. “Shana did a good job of talking to Roseann,” Salter recalled. “She asked her what was going on to keep her conscious.”

Someone secured an air cast to Sdoia’s leg, and then a backboard materialized. Salter, Cottone, and others helped to secure her body to the backboard, and then the firefighter arrived, a veteran named Mike Materia who’s served three tours in Iraq. He held Sdoia’s head, waiting in vain for one—just one—ambulance to stop. But none did—they were filled with other victims.

Eventually, Cottone stopped a prisoner transport vehicle and she, Salter, and Materia—as well as a pair of other firefighters on the scene—lifted Sdoia into the police van. From there, she was transported to the Massachusetts General Hospital, one of some 260 bombing victims on that fateful day.

Salter did not immediately know what happened to Sdoia, whether she lived or died. He struggled to sleep through the night, he later told reporters, and questioned the efficacy of his selfless act. Sdoia, for her part, described the college kid to journalists as her “mystery angel,” and wondered whether she would ever meet him. She recognized him in a photo from the scene—an image of him applying the makeshift tourniquet to her leg—but she did not know his name, nor he hers.

Then, a breakthrough: A few weeks after the bombings, Boston.com ran the photo. One of Salter’s friends posted the image to Facebook, and a local news station called him up, wanting to run a segment on his heroics. The story aired, and then he got another call: Guess who.

In short order, Salter and his family were visiting Sdoia at the Spaulding Rehabilitation Hospital, where she was convalescing following the amputation of her right leg below the knee. “It was a pretty unreal feeling to be reunited with her,” Salter recalled. “It was one of the best feelings I’ve ever had in my life.”

He reconnected with Cottone and Materia too—the firefighter is now the real estate executive’s boyfriend—and the four random people quickly formed an unbreakable bond. Salter and Sdoia, who has learned to walk on an artificial limb, recently participated in a 5K Run/Walk in Lowell, Massachusetts. “That was the first time that I’ve gone on a lengthy trek with her,” Salter said. “She’s definitely trying to push the limits and make her new reality as close to normal as possible.”

He added: “She’s accepted what happened to her and decided to keep moving forward with her life. After seeing that, I’ve tried to adopt that mentality and accept things for what they are.”

Sdoia surprised Salter on Thursday evening, presenting him with the inaugural Shores C. Salter Award for Outstanding Citizenship at the annual Student Life Awards ceremony. The award honored Salter’s bravery, courage, and compassion in the face of chaos, and will heretofore recognize students that make outstanding contributions to the local or global community through service, leadership, and dedication.

“There is no one that reflects [Northeastern’s] values as much as Shores,” said Sdoia, who gave Salter a big hug when he stepped up on the Curry Student Center Ballroom stage to receive his award. “In an instant, without hesitation, he ran into the chaos and tried to make a difference.” She added: “He helped to save my life and would become part of my family, as I would become part of his.”

Salter, who received a standing ovation at the awards ceremony, noted that his definitive plans for the 119th Boston Marathon are still up in the air, but acknowledged that he’d be seeing his trio of new friends at the iconic race. “The marathon bombings were awful and horrible, but some good has come out of that day,” he said. “It united the four of us, and we’ve been able to keep that relationship going.”