Diane Keaton is here to confess.

Back in the 1970s and '80s, while she was jet-setting around the world, collecting awards and establishing herself as America's favorite on-screen eccentric, the actual eccentric in her family, her younger brother, Randy, was living in squalor in Orange County, California, being terrorized by low-flying jets and attempting to gas himself in the garage.

She couldn't really be bothered to check in on him, never mind try to help.

"I wanted to be a movie star," she writes in her new book, "Brother & Sister." "I wanted people - lots of people I didn't know - to love me."

She's still getting that wish. When Keaton, 74, showed up at Sixth & I synagogue in Washington, the heavily bifocaled crowd was there to adore her.

They had paid $40 each for a seat and a copy of the book and the opportunity to bask in her presence for approximately 45 minutes, no photography allowed, no on-the-spot questions from the audience, no meet-and-greet afterward.

It was a rigid program for such an intimate topic. ("Forty-five minutes?" grumbled one woman as the crowd waited for Keaton.) But any time at all with Diane Keaton was coveted, and her fans were ready to take whatever she was willing to give.

It has been that way for decades now, but not always. Before she was an Academy Award-winning actress, Woody Allen's muse (and lately his defender) and a Hollywood icon, Keaton was a big sister in Southern California, the oldest of four - including Randy, with whom she shared a bunk bed. They were close, even if she often thought of him as a nuisance. And she could tell that he was troubled, even back then, by the way he would breathe at night.

"I remember glancing down from my top-bunk apartment in the sky and seeing Randy's anxious bobbing head, his fear of the dark, and his sweet if hapless face," she wrote in her book. "Why was he such a chicken? Why couldn't he stop seeing ghosts that weren't there lurking in shadows?"

"Brother & Sister" is a reconstruction of their lives - from those childhood nights to the darkness that followed Randy into adulthood, which included alcoholism, joblessness, divorce, isolation, fantasies about violence against women and a suicide attempt - told through journal entries by Randy and their mother, along with Keaton's recollections. The sister rises ever higher. The brother sinks ever lower.

Ultimately, it's a story about regret. Randy is unwell now in a different way - incapacitated by Parkinson's and dementia, confined to assisted living, unable to weigh in on his sister's book project. In piecing together the artifacts of their separate memories, Keaton admits that she doesn't know whether "I've gotten any closer to who he is and what he means to me, but I do know that I wish I could have given him more love and attention sooner."

Love and attention for Keaton was in ample supply, however, at Sixth & I when she flounced onstage in a wide-brimmed fedora and a long plaid coat over a black turtleneck, the whole affair cinched at the waist with a thick, shiny belt. The woman who had been grousing about the brevity of Keaton's appearance cheered - all was forgiven! - and the whole crowd stood and applauded while Keaton smiled and politely waved away their adoration.

She blew into the microphone. "Is this on?"

A collective nod.

"Oh, you can hear me? That's too bad."

Laughter.

Keaton's self-deprecation reads like vulnerability, but it can be distancing. She seems to want us to know everything and nothing. It was in her posture, too, sitting onstage swaddled in layers of clothes, sleeves drawn over her thumbs, only her face and fingers and lower shins uncovered in the spotlight. This encounter would be exactly as intimate as Keaton would allow it to be.

"Is there one question that you hate to be asked?" asks the moderator.

"Almost all," Keaton responds.

The audience laughs, and she blows them a kiss.

She wrote the book for us, she says, as much as for Randy.

Relatability is a goal. She knows her story - their story - is unusual: her extreme success and fame, his extreme psychological turmoil. But she says she hopes readers will still see something of themselves in it, of the challenging relationships they have within their own families.

"There are so many people who live through the pain of having a family member who doesn't quite fit in," she told the nodding crowd. She said she wanted to open up a dialogue about mental health and to offer herself up as a cautionary tale that could inspire people to "be better" to their loved ones sooner than she had.

The final chapters of Keaton's book are as much a love letter to her brother as they are an apology. She is sorry for abandoning him, grateful she got him back. Over the past 12 years, as dementia softened Randy's resistance to his family and age tempered Keaton's blinding ambition, the two began spending time together.

Every Sunday she visits. Before he was in a wheelchair, they'd take walks to get ice cream; now, she and an aide push him along. "He would see something - find a leaf or even a bottlecap - and find it fascinating," she told The Washington Post in an interview. "All I remember about that was how special those times were with him. It was like opening something up to me. Giving me such a gift."

Keaton wanted to return the gift by sharing those softer parts of her brother with the world. Part of her motivation in putting together the book, she told The Post, was to give Randy's poetry an audience. Maybe it would catch an editor's attention. "At some point," Keaton mused, "maybe someone will come and look at his writing and really take it and see what they feel he did with it."

Maybe the sister could help the brother get some love and attention for himself, belatedly.

Like many loving gifts, it might reflect her own tastes more than his: Randy never sought fame or recognition. In the book, she recalls him once telling her, "I still believe a small, personal life can produce heroes."

Onstage at Sixth & I, the questions pre-submitted by audience members had nothing to do with Randy's work. They had to do with "Something's Gotta Give," "The First Wives Club" and "Father of the Bride." With whether Keaton has a favorite co-star.

"I don't have a favorite. Do I? No. No, no, no. Not him. ... Not her ... I don't know what I'm talking about. I liked them all," she said. "They had to kiss me. I liked every kiss."

Keaton made sure her brother's presence was felt, too. She stood to read a final passage about a series of nonsensical comments Randy had made after watching "Gone With the Wind" in a room full of Alzheimer's patients. "I keep forgetting that when I die there will no longer be live television," she recalls him saying. The exchange revealed the extent of his delusion, but, when retold to her audience, it also got a laugh.

And it got Keaton a few feet closer to the door. After exactly 45 minutes, she was gone, skittering offstage without so much as shaking the moderator's hand. Not, presumably, out of rudeness, but out of Diane Keaton-ness. Out of her special brand of daffy aloofness, off-kilter and lovable and just out of reach.

We are who we are, brothers and sisters.

"So entertaining," a middle-aged audience member said afterward. As she stood to leave, she shoved Keaton's hardback confession deep in her purse and said: "I'm going to go watch all of her films again."