One by one, they're taking the witness stand at the Bronx courthouse to testify about the terrible fire four years ago this month that killed two firefighters and left four critically hurt. Firefighters caught in the midst of the inferno. EMS workers who responded and saved incredibly injured victims.

One by one, they symbolize the real heroes of the Bronx.

Three people and the company that owns 234-236 E. 178th St. are on trial for carving up apartments there into an illegal warren that trapped six firefighters in a blaze on Jan. 23, 2005, which came to be known as Black Sunday.

The six were forced to jump from the fourth floor to escape flames and smoke. Lt. Curtis Meyran and Firefighter John Bellew died. Firefighters Brendan Cawley, Jeffery Cool, Eugene Stolowski and Joseph DiBernardo survived.

These people deserve the nickname - "the Bravest" - that has been so overused. Not every firefighter is one of the Bravest, just as not every cop is a Finest.

But these firefighters truly are.

They are the ones who want to work in the busiest firehouses, perform the most daring, dangerous work.

Patrick McKenna, who testified that the fire grew into an inferno in an illegally partitioned room, was named a Daily News Hero of the Month for rescuing a woman from a flaming fourth-floor apartment. They dangled on a rope in black smoke, the woman screaming the whole way down.

In this same courthouse in a few weeks, another Bronx firefighter will appear before a judge, but this time no heroism will be on display. Firefighter Nicholas Vrettos represents anything but bravery.

The six-year firefighter from Ladder Co. 53 on City Island is charged with falsely reporting fires.

Within a half hour of a fire chief's visit to Ladder 53 last month to announce the company would be closed at night due to budget cuts, 12 fake calls came in, including one reporting a fire in the cafeteria of a school in session.

The fire companies rushed out each time.

Vrettos allegedly got other people to make calls, but could he could hardly be called a mastermind.

"The idiots used cell phones," said a source. "One guy called and the fire dispatcher asked for a callback number, and he said, 'I don't want to get into that,' and a police dispatcher listening in read him back his cell phone number."

The Department of Investigation, which was notified by the FDNY that a firefighter was implicated in the false alarms, traced one 911 call to a City Island auto body shop that Vrettos operates.

It's the first time in memory that a city firefighter is accused of this disgraceful and dangerous act.

Sources say he allegedly did it because he thought the cutback would mean he'd be transferred to another (translate busier) firehouse.

"We have trouble staffing that firehouse because it's quiet, it's dead there, and most people want to work in active houses," said a source. "He was willing to work there, so he wouldn't have been transferred."

Ladder 53 is one of the quietest firehouses in the city. There was a two-alarm, predawn fire on City Island last week, in a row of buildings, but fire officials said that in the first 10 months of 2008, Ladder 53 did not respond to any overnight fires.

The firefighters who take the stand this week have seen a lot of action. They've saved lives. They have a special vitality.

Think about Cool, who joined Rescue 3 right after 9/11 to fill a void left by a firefighter friend from the rescue company who died at the World Trade Center. Six months before Black Sunday, he rappelled off the flaming roof of a four-story building, grabbed a man from a top-floor window and brought him safely to the ground.

On Black Sunday, he broke both legs, his pelvis and lost 46 pints of blood from internal injuries.

I talked to him when he was in a rehab center, learning to walk again. He kept saying he wished he could go back to fighting fires. He couldn't. Last week, I still heard regret in his voice over the loss of the job he loved.

Stolowski's legs, ribs and pelvis were shattered in the fall, and his skull became detached from his spine in an internal decapitation. He can't move his neck. But he wanted to contribute, to continue to serve the city.

He has a pleasant, upbeat demeanor, and works with the FDNY Fire Family Transport Foundation, which assists injured firefighters.

Cawley suffered serious chest and back injuries and a brain hemorrhage. He could have retired with a tax-free disability pension. But he went back to full duty at busy Ladder 27.

Hopefully, the trial will be finished before Vrettos shows up in the courthouse to tarnish the badges of real firefighters, truly the Bravest.