Protesters declare 'I am Trayvon Martin,' but who was he?

Miami (CNN) -- "I am Trayvon Martin" has become the catchphrase for protesters expressing solidarity with the slain Florida teenager and outrage over his killing. Even President Barack Obama declared, "If I had a son, he would look like Trayvon."

But who really was Trayvon Martin? There is plenty of speculation, including some bloggers who point to his recent school suspensions -- including for drug residue in his backpack -- and images of him sporting tattoos and a what appeared to be a gold tooth grill as possible evidence of a troubled teen.

That portrayal is in stark contrast to the accounts from his family, friends, and teachers who described Martin as an average 17-year-old.

"He was a shy kid," said family friend and former football coach Jerome Horton. "He didn't want to be the center of attention; that's just not him.

"He always walked with his hoodie and his headphones," recalled Horton. "If he wasn't on the phone, he was listening to music -- anyone that knows him knows that."

Just like most any other teenager, Martin enjoyed listening to music -- R&B was his favorite -- going to the movies and the roller rink with his friends, friends and family said. When Martin entered high school, his childhood goals of a career on the football field were replaced with his dreams of working with airplanes.

"He just loves getting on planes," said his father Tracy Martin.

During the summer of 2009, his parents -- who separated when Martin was 11, but shared custody -- enrolled their 14-year-old son in "Experience Aviation," a nonprofit program in Opa-Locka, Florida, that introduces young people to aviation.

Trayvon Martin, at age 14, with pilot Barrington Irving at his youth aviation program.

The seven-week program is the brainchild of Barrington Irving, the youngest person ever -- and the first black pilot -- to fly solo around the world, a feat he accomplished in 2007 at the age of 23.

Irving remembered Martin as "a polite kid" who enjoyed flying.

"When I first met Trayvon he had a strong interest in football. He reminded me of myself because I had a strong interest in football until I fell in love with aviation," said Irving.

After graduating from the program, Martin spent the following summer as a volunteer, assisting new students enrolled in the aviation program.

During high school, Martin also volunteered his time at the concession stand at Forzano Park where he played football since age 5, on a team coached by Horton and his father.

"He would literally go to school and from school he would go to the park to volunteer to maybe about 8, 9 o'clock and go home," said Horton. "That was Trayvon's day, his week."

Martin's mother transferred him from Miami's Carol City High School to Dr. Michael M. Krop High School, closer to her home.

"He was doing average in school, a little bit better when he was at Carol City and then I had him transferred,'' Sybrina Fulton said, according to the Miami Herald. "I thought Krop was a better school and I wanted a different environment for him. My oldest son has graduated from there.''

In his junior year at Krop, Martin's favorite subject was math, according to his father.

"He was just an average student," he said.

Trayvon Martin, 17, in an image taken less than two weeks before his death.

At Krop, Martin was suspended three times, according to records obtained by the Miami Herald, once for writing graffiti on a door and another time for school truancy. The third suspension took place the week of his death. Martin was suspended for 10 days due to drug residue being found in his backpack.

In an interview with CNN's Anderson Cooper, Sybrina Fulton responded to her son's suspension: "Whatever he had dealings with the school, it was not criminal, it was not violent, he's never been arrested."

Darrell Green, a fellow football player and close friend, said Martin was no different from any other teen.

"Everybody gets in trouble," said Green, "Everybody goes through it."

Green remembered Martin as a "positive person" and a "good friend."

During the 10-day suspension, Tracy Martin took his son with him to Sanford, about four hours away from Miami, while he visited his fiancée because neither he nor Fulton wanted their son to stay in his hometown where he could enjoy his friends, said Horton, who has been in close contact with Martin's father.

"He wasn't just suspended from school and up at Sanford kicking it and having a good time," said Horton. Martin had only been to Sanford a handful of times.

Sybrina Fulton and Tracy Martin spoke to Democratic lawmakers Tuesday on Capitol Hill.

His fateful walk to the convenience store for a bag of Skittles and an iced tea on the evening of February 26 happened only because the teenager pleaded to leave the apartment, said Horton.

"The only reason he got a chance to go to the store is because he begged his dad to go," he said. At the time, his father and his fiancée had gone out to dinner and to watch a basketball game, leaving Martin at the townhouse, according to Martin family spokesman Ryan Julison.

While walking to the store, Martin was on the phone with his girlfriend, whom he had been talking to for over 6½ hours throughout the day, the family's attorney said, citing phone records. The girl, who did not want to be identified, said she told Martin to run, but he refused, the family attorney said.

"What are you stopping me for?" Martin asked a man later identified as neighborhood watch captain George Zimmerman, according to the girl.

"What are you doing around here?" Zimmerman asked in response.

The girl said she then got the impression that an altercation was taking place and that someone had pushed Martin, because the headset fell out of his ear, and the phone shut off.

Moments later, Martin was shot and killed. The details of what happened are still murky. Zimmerman has said through his legal adviser that he acted in self-defense after Martin attacked him. The family disputes that, and witness accounts vary. Fulton told CNN's Piers Morgan that she believes Zimmerman "hunted my son like an animal."

The teen's killing has captivated the nation's attention, with some saying this shooting of an unarmed teenager has exposed underlying racism. Some also feel that it's better to wait on the evidence before rushing to judgment on what happened that night.. Others decry the "stand your ground" law that allowed Zimmerman to walk away free of any criminal charges.

As these broader issues continue to dominate the news headlines, the only thing that is certain is that Sybrina Fulton and Tracy Martin have lost their son. When asked for one word to describe Trayvon Martin, Sybrina Fulton chose "lovable," adding, "I miss his smile."

Asked what he would say to Zimmerman if he had a chance to speak to him, Tracy Martin had many questions:

"I would ask him why did he in fact pick out my son, what was going through his mind that night?" Martin told Piers Morgan. "[Did] he realize he's destroyed an innocent child's life? My son had a future. My son was not one of these thugs in the night.

"I would ask him, why did he in fact take my son's life and how does he feel about taking my son's life?"

CNN's George Howell and Vivian Kuo contributed to this story.