Andrew Kessler, 18, is a sweet boy, but because of autism and his inability to communicate, he lives an isolated life.

He can't play team sports. He had no friends.

"He can pogo-stick and hula-hoop like nobody's business," said his mother, Cindy, but connecting with the world, being active, is hard.

When Luke, his younger brother, joined Haddon Township High School's state championship cross-country team, the whole family was transformed.

"Andrew was always there and watching and seeing all the excitement," Cindy said.

So was her husband, Chris. He had long believed running was boring, but cross-country meets were riveting - and they motivated him to get off the couch.

At age 62, Chris Kessler started running.

And his wife suggested he take Andrew with him.

"Frankly," said Chris, "I thought she was crazy."

Chris felt there was no way Andrew could keep up, much less enjoy it.

They started running together in the neighborhood, then on Wednesday nights last summer with the South Jersey Athletic Club.

"He kind of took to it," said Chris. "He doesn't get the nuances of baseball, or an end-around play in football. But he totally gets running down the block and beating somebody from point A to point B, and it tickles him."

At a meeting of the athletic club, Chris heard a presentation from Achilles, a group that runs with the disabled and builds esteem. Achilles was starting a Philadelphia chapter.

Chris started taking Andrew on Saturdays last fall.

Andrew loved everything about it - the outing with his father, the camaraderie - and, of course, the running.

"We always ran together," Chris said. "Andrew's autism seemed to dictate that. His lack of language made it very difficult if not impossible for him to explain even the simplest predicaments. He needed me to run with him, to read his nonverbal cues and interpret for him."

Chris began dreaming about the Broad Street Run - 10 miles through the heart of the city, crowds cheering. Andrew would be like everybody else, just another runner in the epic race sponsored by Independence Blue Cross. What an achievement it would be for both of them.

They were on schedule. But in February, Chris broke an ankle on a run.

"I thought our dreams of Broad Street would have to wait," Chris said.

But Melissa Wilcox, who founded the Achilles chapter, and Rodney Russen, a volunteer, had other ideas.

"The second time I met Andrew," said Wilcox, "I was greeted with a huge smile and bear hug from him. Since then, his hello and goodbye hugs are one of my favorite parts of our Saturday workouts."

Wilcox felt she and Russen could train Andrew - without his father.

Chris and Cindy were terrified, but relented.

"We had to be careful," said Wilcox, "not to push him too far or too hard, knowing that if he is really hurting, he may be unable to tell us."

Andrew has blossomed into a runner, a teammate. "The results have been amazing," said his father, "and he runs with a joy that's infectious. In fact, freed from training at my plodding pace, his fitness level is better than ever."

Wilcox and Russen have been training with Andrew during the week as well. Last week they ran nine miles at an 8:18 pace.

"I can't wait to watch Andrew and his Achilles teammates cross the Broad Street Run finish line," said Chris. "I'm predicting goose bumps and tears. It should be epic."

Andrew doesn't understand what happened in Boston, Chris said, but he will wear red socks to show his solidarity. "My prayer," says his father, "is that the anticipated outpouring of love and support for the victims and Beantown during the BSR will in some small way help the healing process."