"Rodgers? I'd like you to meet Hammerstein. Hammerstein, say hello to Rodgers."

"Andrew Lloyd Weber, this fella here is named Tim Rice."

"Ira Gershwin, do you know George Gershwin? Oh, wait. You're brothers..."

All partners in the lore of immortal Broadway collaborations had to meet somewhere, right? And how many of them knew instinctively that theirs would be a fruitful relationship of greatness?

Aryanna Garber and Benjamin Velez, in Waterford nuancing the dawn of a collaborative journey with their musical "Borderline" at the Eugene O'Neill Theater Center's National Music Theater Conference, didn't initially agree on compatibility.

"I thought our first meeting went terribly," Velez says.

"And I thought it was the best meeting I'd ever had," Garber says as they both laugh.

"Well, she was nervous," Velez explains. "If you're meeting a possible collaborator for the first time, sussing each other out on what could be a long project, it can be awkward."

The two met a few years ago after Garber came up with an idea for a story based around a smart, funny but floundering young woman named Anna who is coming to terms with a recent borderline personality disorder diagnosis. Having flunked out of college, Anna moves back in with her soon-to-be-remarried father and an array of therapists to help her deal with a mental health issue she's reluctant to admit she has.

Garber originally thought "Borderline" would be a screenplay, then realized a musical might be the best way to integrate audiences into the complex dynamics of the character's mental health issues — and, from an audience perspective, a limited awareness of a condition that impacts how a patient thinks and feels about him- or herself and others, and often makes it difficult to function in everyday life.

But a musical presented Garber with a problem.

She has many talents and credits: a master's degree in narrative medicine from Columbia; personal assistant for bestselling novelist Erica Jong; worked with Emmy award-winning director Stephanie Laing on the HBO series "Veep" and "Vice Principals"; and head writer on Laing's new "Pypo" digital comedy network.

But she's not a songwriter.

Garbner was describing this dilemma to a colleague, who said, "Oh, you should meet my friend Ben."

She was referring to Benjamin Velez, a composer and lyricist whose musical "Kiss My Aztec," with its book by John Leguizamo and Tony Taccone, made its world premiere at Berkeley Rep earlier this month. Velez has also been a Sundance Artist and has two other musicals, "Starblasters" and "Afterland," in various stages of development. He's currently a 2018-19 Dramatist Guild Foundation Fellow.

Despite any shaky impressions at Garber and Velez's initial get-together, it worked out. Garber sent Velez the story and background material on borderline personality disorder, and it immediately hooked the composer. Garber's vision of the story was that there is a darkly comic vulnerability and determination to Anna.

"I got so inspired by the story and characters and possibilities," says Velez on Monday, shortly after the pair arrived at the O'Neill Center. He'd taken a redeye Sunday night from Los Angeles, picked up Garber in New York City, and the two drove straight to Waterford.

"Borderline" is the first of three musicals that will be workshopped over the course of the conference. It debuted Saturday and continues with performances in the Rose Barn Theater today, Wednesday and Friday. Between shows, plenty of rehearsals and fine-tuning take place.

The other two musicals in development at the conference are "Jeanette" (with presentations June 29 and 30 and July 3 and 5) and "The Undesireables" (July 6, 7, 10 and 12).

Recalling his excitement upon receiving Garber's material, Velez says, "I immediately wrote and sent her the first song, and she loved it. I wrote so many songs so quickly; I've never written the first draft of a show that fast. A lot of those songs were ultimately cut, but that's part of the process. What's important was that I definitely connected to the story and the idea of collaborating with Aryanna."

Garber was relieved and energized.

"Mental health is a delicate subject," she says. "I had decided — hoped — that the structure of a musical would provide the audience with the best entrance into a realm that's otherwise difficult to access or understand. We're dealing with both subjective and objective points of view in showing Anna's world. There are doorways for both, and it's important to make sure everyone feels intrigued and welcome in that world. And it was immediately clear from Ben's songs that he got it."

Listening to samples of the score, Velez's tunes offer a kaleidoscopic fusion of pop hooks, jazz harmonies, a funk groove at the core, and also haunting balladry that reflects Anna's chaotic humanity and a dawning realization that she must admit she's sick before she can move forward with life.

At the conference, Garber and Velez will work on the production with director Jaki Bradley, music director David Gardos (and a full band), dramaturge Carrie Chapter, and a cast that includes Florrie Bagel, Charl Brown, Lincoln Clauss, Matt Dallal, Sarah Lynn Marion, Gilli Messer, Andy Taylor, and Tatiana Wechsler.

"Working with Benjamin became a partnership in the best sense, and we established that trust that you have to have," Garber says. "There's a comfortable give and take, and we just work really well together. We can sit for hours and go back and forth."

"I don't know that I could have written this with anyone else," Velez says. "If I'd just read a textbook on (borderline personality disorder), I wouldn't have grasped it. I found ways to channel Anna through music that I wouldn't have been able to with anyone other than Aryanna. She's so smart and has a very funny but dark sense of humor, and I was able to piggyback on that in so many ways."

Garber and Velez first submitted "Borderline" to the 2018 National Music Theater Conference. It made it to the second round before being accepted this year — when the conference received a record-breaking 320 submissions.

"'Borderline' is just gorgeous and complex. It deals with a stigmatized condition, and Aryanna makes it accessible and takes the audience into that world," says Lexy Leuszler, the literary manager who oversees the submissions process for all the programs at the O'Neill Theater Center. "And Ben's songs capture the difficulties and the sadness and the funny situations, too. We're very excited they're here."

If you go

What: "Borderline" at the National Music Theater Conference

When: 3 p.m. today, 8 p.m. Wednesday, 7 p.m. Friday

Where: Rose Barn Theater, Eugene O'Neill Theater Center, 305 Great Neck Road, Waterford

How much: $30

For more information: (860) 443-1238, theoneill.org