“I just feel more open,” Ms. Geiger said, well aware that emotional intimacy is the lingua franca of a good pop songwriting session. “Because I’m willing to talk about everything now, people are then more open with me.”

She added: “There’s no longer this piece of me back there saying, ‘Don’t go there.’ I used to find that I’d sing songs and think, ooh, it sounds like I’m talking about that stuff, and I don’t want to talk about that stuff. But it was just coming out.”

Mr. Reed said only in retrospect did he notice “these sort of cryptic little hints and clues buried in these half-spoken, half-mumbled melodic passes and demos” — nearly subconscious nods toward struggles with identity. “Teddy was already really open and great to be around,” he said, “but that has increased tenfold. When you feel all of that freedom and honesty, how could you not just radiate it?”

Known as a studio whiz, proficient on every instrument and quick to offer a melody or turn of phrase, Ms. Geiger is also an eternal font of silliness, with her affinity for inside jokes, arcane YouTube videos and nonsensical, pun-heavy ditties well-known to all collaborators. Musically, she specializes in what she called “roughing up pop music a bit,” leaning on organic rock instrumentation in a digitized world and hoping to keep the radio as idiosyncratic as possible. (A track she is producing for Ms. O’Brien is built around a cellphone recording of Ms. Geiger making a beat on the tab of a beer can while at a house party.)

Justin Tranter, a fellow pop songwriter who also started in scuzzier bands, called Ms. Geiger a “musician’s musician” — one whose coming out helps to shift the landscape for queer creators.