Convicted cocaine dealer Charles Lewis told jurors this week that he began cooperating with authorities investigating D.C. Mayor Marion Barry because his own legal troubles gave him an ethical "wake-up call" to come clean.

But there are those in Washington who would say that Lewis is really saving his own skin by betraying a friend -- if the two were ever "friends" in the first place.

"If I really thought someone to be a friend, I wouldn't expect them to testify against me," said Anita Tillman, 27, a claims adjuster who attended the first and second days of Barry's drug and perjury trial. "Then again, it's hard to say what you might do if you're facing 20 years in jail."

Tillman added that from what she heard of Lewis's testimony, "I didn't know that they were friends. They were people who met each other and found a common bond: drugs. There wasn't anything except the drugs."

But for others, such as Lillie Bates, 77, a deaconess for 50 years at Shiloh Baptist Church in Northwest Washington, silence between friends is sometimes golden.

"Take Reagan's case," Bates said. "Some of the people who would not speak out, I think they were true friends of Reagan, because some of them knew he was involved in Iran-contra."

But, Bates said, friendship sometimes changes, as in the mayor's case.

"When they were together, I think Charles Lewis was a true friend of the mayor. Then {Lewis} got into trouble and tried to bail himself out. He defected from his friend," Bates said. "I would think he was a fair-weather friend."

Lewis is the first in a long line of one-time friends, associates and girlfriends who are expected to testify for the prosecution.

Their scheduled testimony challenges the notion that friendship is sacred, as portrayed in the song by Dionne Warwick:

Through good times

Through bad times

I'll be at your side forever more

That's what friends are for.

The idea that some of Barry's friends were the fair-weather kind was first articulated by the mayor himself after his arrest and treatment for substance abuse.

"Look out for your friends," he told members of the Mayor's Youth Leadership Institute in March. "I've got some friends, laugh and grin in my face, ain't worth a {expletive}, you know."

On Monday, Barry told city workers, "I've changed some of my friends around, I'll tell you that . . . . My grandmother taught me, whenever you make a friend, remember that person may be a potential enemy. So be careful."

Last week Barry, apparently referring to Lewis and others preparing to testify against him, called them "canaries," underworld lingo for government witnesses.

Before the start of testimony, Barry joked with reporters in the courtroom, "Come to hear the canaries sing?"

Lewis himself is unsentimental about his ties to Barry. While being cross-examined yesterday by Barry's chief attorney, R. Kenneth Mundy, Lewis said that Barry "wasn't a friend of mine."

But, Mundy asked, what about the times they spent together in the Virgin Islands, sharing girlfriends?

Lewis responded, "He felt comfortable with me and I felt comfortable with him on those short occasions."

Lewis testified that that didn't stop him from traveling to Washington to ask for Barry's help in landing a part in a movie.

Felicia Williams, 26, a saleswoman at Hechts in downtown Washington, has strict requirements for true friends, and a few words of advice for Barry: "To make a friend, you really have to communicate, talk," Williams said. "Someone can be a friend, and then again, they can just be a hang-out partner. I'd depend more on my friends."

Williams did not think lying was too much to ask of a friend. "If it's a friend, automatically a friend's going to lie for you," she said. "If you're an honest and trustworthy friend, you're going to lie to help your friend."

But for many others, such as Shirley Watterson, 50, a federal worker having lunch on Pennsylvania Avenue NW, lies and friendship are incompatible, in public and in private.

"Friends are honest. That's part of what friendship is about," Watterson said. When it comes to a court of law, she said, "It's a completely different ballgame. It's their obligation, first, to be honest. That has nothing to do with friendship. The law is the law."

People had many definitions of what being a friend entails, but they agreed that Barry probably needs to revise his criteria for friendship.

"People that are involved in drugs and the drug world, you cannot call them friends," said Robert Ealy, a 40-year-old manager of the Golden Dome arcade at 14th and K streets NW. "They're using you, abusing you, and not helping you. They're taking care of themselves, watching out for their own interests."

In the mayor's case, said John Williams, 23, a Howard University student working at a law firm for the summer, "Evidently, the price of friendship is saving yourself."