Patrick Fitzgerald seems to brace against the condolences as if they were winter winds. Patrick wishes they would stop. This must be so painful for you. We're so sorry.

"How do you respond to sympathy?" he asks. It is a question to which a teenager should not yet have an answer.

We are sitting in a small cafe a block from the school where Patrick is a senior. Recently his best friend jumped off the Golden Gate Bridge. Jonathan Zablotny rose at 6:45 on a Tuesday morning, showered, ate breakfast and left for school, a five-block walk from his home. He never arrived. Pedestrians on the bridge spotted his body at 4:46 that afternoon. His backpack, with his books and binders, was still strapped to his back.

When Jonathan's parents called with the shocking news, Patrick remembered a story he had read in the paper just eight days earlier. It was about mental-health advocates pushing, yet again, for a suicide barrier on the Golden Gate Bridge. Patrick had tossed the story aside. It had nothing to do with him.

But in one moment, as he imagined the ease with which his best friend climbed over the bridge railing, a suicide barrier became the most obvious thing in the world. Of course there should be a barrier, he thought. Jonathan would still be alive. Bridges without them make suicide too easy.

When Patrick hung up the phone, he poured his anger and loss into an elegant and powerful letter to the Golden Gate Bridge board, and printed up petitions that he distributed the next day at school.

"The petition was pretty much all I could think about for a week," Patrick says. He is still collecting signatures and plans to present them to the board at a coming meeting.

"This movement to get the barrier is my expression of grief," he says. As he wrote in his letter, "These words are my tears."

The emergency phones, which link callers automatically to suicide counselors, aren't enough, Patrick says. The suicide patrols, added in 1996, also aren't enough. Every year, about 18 to 20 people still kill themselves by leaping from the bridge; more than 1,300 have done so since the bridge opened in 1937. Most of the objections to the barrier have to do with cost and aesthetics. But if the Parisians could stomach a suicide barrier on their beloved Eiffel Tower, Patrick wonders, why can't San Franciscans tolerate one on the bridge?

Jonathan's father, a psychiatrist for 25 years and medical adviser to the Depression and Bi-Polar Support Alliance, has served for years on his hospital's suicide review committee. He resigned after his son's death. "I can't do it anymore," Ray Zablotny says, sitting with his wife, Mary, in their living room.

He says Jonathan showed no signs of mental illness, much less signs of being suicidal. The trigger, he says, seemed to be schoolwork. He was bright, scoring 1400 on his SAT. He had applied over the Christmas break to several top-end colleges. But he struggled with an almost paralyzing inability to get himself started on projects and reports, a problem that caused frequent clashes with parents and teachers.

The week he killed himself, seniors at his high school had a battery of research papers due that would weigh heavily on their grades. Jonathan, his parents discovered the day before he died, had not even started on his history paper on the 1986 Challenger explosion. He would fail the course if he didn't turn it in. His parents confronted him. They had just gone through the same infuriating routine in getting him to write his college-entrance essays.

"I apologized the next morning for yelling at him," Mary Zablotny says. "But I think maybe he was balanced on a knife blade all day."

Jonathan seemed to stave off anxiety and feelings of failure by escaping into fantasy games. The boys seemed to revel in their eccentricities. Patrick, pale and bony, wears a beret to school and seems to disdain most of popular culture. Jonathan, tall and gangly, was such a zealot about recycling that classmates sometimes dropped glass bottles in the trash just to taunt him, knowing he would fish them out.

"I think Jonathan has always been a little depressed," Patrick says, adding that his friend was never, ever suicidal. His leap from the bridge was an impulse.

"He didn't stop to think that everything (the research papers) would have been over in a couple weeks, and all the stress would have been gone," Patrick says.

A few days after his death, Jonathan's aunt came across what seemed to be a suicide note on Jonathan's computer. It was not dated but was the last file in his school folder. It was addressed not to his parents or to Patrick but "to whom it may concern."

"I'm a coward. I'm taking the cowards way out and it should be honestly said what has happened. I have struggled with the same problem for 6 years and it is painfully obvious to me that I cannot overcome it for any length of time and be happy. Jonathan Zablotny."

His parents believe the problem refers to his struggles with getting his schoolwork done. Patrick says no one will ever know for certain what drove Jonathan so suddenly to the bridge.

He isn't sure when he will go to the bridge board to present the argument that has been presented so many times before. But Patrick knows his argument is different. He knows that every suicide off the bridge is different. Every single one shatters entire universes. That's what people don't get, he says - what he didn't get - until it becomes personal. He knows the board has never heard what he wants to tell them because no one has ever had a friend exactly like Jonathan.

Joan Ryan is a columnist for the San Francisco Chronicle. Send comments to her in care of this newspaper or send her e-mail at joanryan@sfchronicle.com.