When the bombs went off at the Boston Marathon in 2013, Rachael Cooper's first thought was that a car had backfired.

Her second was about her sister, Madeline, who had not yet reached the Starbucks, two blocks from the finish line, where they had agreed to meet after the race.

"Somewhere in there I realized my sister was not standing next to me," said Cooper, a Hadley resident. "I thought, I need to find her now. If that means running towards the finish line, fine."

She felt a touch on her arm and turned to see Madeline; they had finished the race minutes apart. They moved through the chaos to their uncle's apartment near the Boston Common, and to safety. But for Rachael, the day left a scar.

Cooper spent a year not talking about the attack; "I really didn't want it to be something I needed to deal with," she said. But she ran the marathon again in 2014, despite a twinge of nervousness as she turned onto Boylston Street. And this year, she will be facing the bombing head on, with the goal of helping others.

Cooper, along with her friend Chris Laudani and three other team members, is running the marathon as a benefit for a new foundation launched by Carlos Arredondo, the good Samaritan in a cowboy hat who won fame after he was photographed helping save the life of marathon bombing victim Jeff Bauman.

Carlos Arredondo, right, helped save Boston Marathon bombing survivor Jeff Bauman, left, after Bauman was critically injured in the attack. Arredondo and his wife Melida have started a foundation to help military families and families affected by suicide.

Arredondo and his wife Melida started the Arredondo Family Foundation in February to help support military families and families affected by suicide. It is an issue intimately close to them. Carlos Arredondo's eldest son Alexander was killed fighting in the Iraq War, and his younger son Brian committed suicide in 2011 after years of depression stemming from his brother's death.

The foundation is in its infancy; it is not yet registered with the IRS and is partnering with the Dorchester nonprofit WORK Inc. to accept donations. The charity is hoping to raise between $50,000 and $100,000 this year to start an emergency fund for military families that have gone through suicide and a veterans' scholarship at UMass Boston. A formal launch party is scheduled for early April.

"Everything moved forward when we found out we could have 5 runners for the Boston Marathon," Melida Arredondo said. "All of this is happening at once."

Cooper grew up watching the marathon from the sidelines, as runners cut through her hometown of Ashland on their way to Boylston Street. She has already raised $2,000 of the $5,000 she is seeking for the foundation. $1,550 of that has come from her online crowd funding drive, which got a boost earlier this month when it was featured in the Daily Hampshire Gazette; the rest, from a more creative fundraiser.

Cooper, a medical assistant at Atkinson Family Practice in Amherst, enlisted her colleagues for a raffle with a unique prize.

"We had a pie-your-doctor fundraiser at work," Cooper said.

On a sunny day near the end of winter, in the practice's parking lot, raffle winners threw whipped cream pies at Dr. Kate Atkinson and four other employees at the practice. The event raised $425, and against the backdrop of the ongoing trial of accused marathon bomber Dzokhar Tsarnaev, reminded Cooper what the benefit was truly about.

"It was what the team stands for," Cooper she said. "This is people supporting people."

Donations are accepted at http://www.gofundme.com/she_runs_again.