Pulitzer prize winner Elizabeth Strout, 68, has wooed readers and critics alike with a string of bestselling novels set in Maine, where she grew up and now mostly lives. Her latest, Tell Me Everything, unites two recurring protagonists from recent books – self-effacing author Lucy Barton and abrasive nonagenarian Olive Kitteridge – with sometime lawyer Bob Burgess, who first appeared in her 2013 novel The Burgess Boys, and is now set to be hauled out of semi-retirement by a murder case. As a New England winter finally yields to spring, pathos and dry humour gild tender reflections on loneliness and connection, and the redemptive power of storytelling.

What made you want to bring all three characters together?
I never ever intend to keep writing about the same people, but it gradually came to me that they are all living nearby. I wanted to get Olive and Lucy together – that was a propelling force. I just thought it would be so much fun, and of course Olive can’t stand her at first. The working title was The Book of Bob because Bob has always intrigued me. He’s such a decent person and doesn’t know that about himself, and I wanted him to come out of semi-retirement and do something big and meaningful.

Did it feel risky?
It felt very risky in terms of, is a reader really going to want to listen to all these different people and follow their different stories?

Is the reader present for you as you write?
Always. I feel like we’re doing this together. Years ago, I made up a reader who sits across the desk from me. They are patient but not super patient, interested but not really interested. It’s my job to take them along and to deliver something that is worth their while.

Lucy and Olive meet regularly to share stories, Olive insisting that a story needs to have a point. Do you agree?
I don’t think stories need points the way people think they might need them. It’s the telling of the story as one person perceives it that’s the point.

Then there’s Lucy and Bob, who develop feelings for each other. No spoilers, but did you have a sense of how their relationship would evolve when you began the book?
I didn’t know what was going to happen and I thought, I’ve got myself into a pickle here. How are they going to live with each other? How are they going to live without each other? I really don’t plan anything as a writer. I wish I could be a bit more organised, but I just sort of splash away.

A recurring lament here is the “mess” that America’s in, with civil war looming as a credible threat. Do you have any hope for the future?
I feel very hopeful some days, and then I get worried about my hopefulness, because don’t forget, I am from New England, we’re not supposed to expect good things, so my hopefulness makes me even more nervous than before, when I wasn’t hopeful. I literally do not have a clue what is going to happen in this country.

The essential unknowability of others – ourselves, even – is an enduring theme. As Lucy says, there’s no knowing what another person thinks of when they wake in the middle of the night. What do you think of?
I’m usually just trying to get rid of dreams, so that I can get back to sleep. I am a tremendous dreamer. My mother died about a year and a half ago and last night I was dreaming that she was in prison. I was thinking, well, obviously that’s a mistake, and then the more I talked to the lawyers, the more I realised they were not telling me the truth. Just as I woke up, I realised she was in there for murdering somebody. Now what in the world is that all about?

Tell us about Lucy and Olive’s shared fascination with stories of ‘unrecorded lives’.
I’ve always been fascinated with this sense that every single person walking down the street has a whole story. It’s so interesting to think about the vast variety of things that can take place within one person’s life, and how nobody ever really knows it, because we only tell parts of our story to different people, and oh, I just want to know it so much! I always have, so I make it up.

Is that what made you a writer?
I just knew I was a writer from a very young age. My mother was an English teacher and I look back now and think she probably wanted to be a writer herself. She certainly encouraged it in me. She had a natural brilliance to her storytelling and would talk about people to me in a way that made them seem so magical.

You were in your 40s before you published your debut novel, Amy and Isabelle. What kept you going?
I realised that every story – I was writing mainly stories – was just a tiny bit better than the one before, but I had to get worn down before I found my voice with Amy and Isabelle. Up until then I had been trying to write like a writer, like whoever was in the New Yorker that week. It was back in the minimalist age, and I finally realised, well, I’m sort of a blabbermouth, so maybe I’ll try to write a novel instead.

Do you think people sometimes confuse you with Lucy Barton and her traumatic childhood?
I think that people probably do, but I don’t worry about that any more. She’s very accessible to me, I feel like I really know her, but the only thing I did have in common with her in my childhood is isolation. We lived on a dirt road outside town, so there was that sense of being away from other people.

What are you currently working on?
I don’t usually talk about it, but I’m working on an entirely different person. A man who is not from Maine, and I just adore him. He’s a school teacher and he’s so ordinary but he’s not, because all ordinary people are extraordinary. There’s an awful lot to him.

Any chance you’ll be revisiting Lucy, Bob and Olive?
I don’t know; but I do know that no matter what happens, Olive Kitteridge will never die on my watch.

What are you reading at the moment?
Jeffrey Toobin’s American Heiress, about Patty Hearst, is my fun read, and I have also returned to The Journals of John Cheever, which I loved for a number of years way, way back in the day, and then all of a sudden was done with. I found a copy and was curious as to what I had underlined and who was I 30 years ago? They’re different to me now, and interesting. I also have James by Percival Everett sitting here waiting for me.

Is there a book you regularly return to?
The Collected Stories of William Trevor. I have a copy upstairs and a copy downstairs. The stories are so gentle and beautiful and haunting. I will very often pick one up before I go to sleep.

• Tell Me Everything by Elizabeth Strout is published on 19 September by Penguin (£16.99). To support the Guardian and Observer, order a copy at guardianbookshop.com. Delivery charges may apply