There's a little free library on my street. A wooden box on a post, holds maybe ten books. Last month I left my favorite book in it — the copy with all my notes in the margins. 'This line got me.' 'Nobody recovers this fast.' 'I'd forgive him too.' Today it's back. Same coffee stain on page 41. But under every note of mine, someone wrote back in blue pen. Under 'I'd forgive him too' it says: 'You would? I've been arguing with you about this for a month.' I don't know this handwriting. I check the street. Empty.

I don't write anything. Not yet. I want to know who I'm talking to. I put the book back in the box, exactly how I found it. Then I set up on my porch with coffee and a clear view. Two joggers. A beagle. The mail carrier waves. 8:40 — someone in a blue jacket stops at the box. Takes out MY book. Flips straight to the margins. And frowns. Because I didn't write back.

I'm off the porch before I can think. Me: 'Any good?' They jump. Hold up the book like evidence. 'Sorry — is this yours? The notes. Are they yours?' Up close: my age. Nervous. A pen tucked behind their ear like they came ready to reply. Me: 'The black pen is me.' They stare. Then: 'You didn't write back.'

I panic and go with a joke. Me: 'I charge for replies now. One coffee per margin.' Silence. One second. Two. Then they laugh — a real one, too loud for a quiet street. 'There's a place two blocks over. They let you sit for hours.' They hold up the book. 'We can grade my replies. I know you have opinions about my take on the ending.' I have SO many opinions about their take on the ending.

The place two blocks over really does let you sit for hours. We test it. They defend their take on the ending for twenty solid minutes. They're wrong. It's adorable. Me: 'You annotated a stranger's book. Who does that?' 'Someone who liked the stranger's brain first.' They slide the book across the table. 'Front page.' The front page has today's date and one new line in blue: 'First coffee. Hopefully not an ending.' It wasn't. We're on book forty-one.