(Luiz C. Ribeiro/Pool/Getty Images; ABC News)

ABC News’ Olivia Katrandjian reports:

“I don’t want to talk to nobody, see nobody, nothing,” Peter Negron said on Father’s Day in 2002, nine months after losing his father in the World Trade Center attacks.  “I just want to go to the cemetery, and say that I love him and I miss him, and then I just want to come home and stay in my room for the whole, long day.”

Peter’s father, Pete Negron, 34, worked as an environmental project manager for the Port Authority on the 88 th floor of the North Tower. He left behind two sons, Peter, who was 11, and Austin, who had just turned 2 years old.

“For months after 9/11, Peter never smiled,” Peter’s guidance counselor, Selma Alaimo, told the Bergen Record in 2002. “This sweet kid looked like he’d lost his very best friend.”

On Sept. 11, 2003, Peter stepped up to the podium at the second anniversary memorial service and recited the poem “Stars,” by Deborah Chandra: “I like the way they looked down from the sky / And didn’t seem to mind the way I cried / And didn’t say, ‘Now wipe away those tears,’ / Or, ‘Tell us, tell us what’s the matter here!’ / But shining through the dark they calmly stayed / And gently held me in their quiet way.  / I felt them watching over me, each one / And let me cry and cry till I was done.”

Peter is one of more than a thousand children who lost a parent in the World Trade Center attacks. The 343 New York Fire Department victims alone left behind more than 600 children.

Today, Peter once again addressed the nation, this time as a 21-year-old young man. He said he’s learned more about his father in the last 10 years. “He cared about the earth, and our future,” he said. “I know he wanted to make a difference.” He wants to do the same.

He spoke of how he has tried to be a father figure to his brother, Austin.

“I try to teach him all the things my father taught me. How to catch a baseball, how to ride a bike,” he said.

“I have stopped crying, but I’ve never stopped missing my dad,” he said, choking up.  “I wish my dad had been there to teach me how to drive, ask a girl on a date, and see me graduate from high school. And a hundred other things I can’t even begin to name.”

“I have decided to become a forensic scientist,” Peter added. “I hope I can make my father proud of the young men me and my brother have become. I miss you so much, Dad.”

When asked in 2002 what he will most remember about his father, Peter said, “That morning, he said, ‘I love you, champ.’”