Liam McGuinnis was Rayna Jaymes' producer and acted as Scarlett O'Connor's producer, also being responsible for giving her prescribed medication to help with her insomnia. The two briefly pursued a romantic relationship.
Rayna Jaymes reads a magazine article on Liam McGuinnis, and decides that she wants him to be her new producer. He's not country, but he's been quite successful, he's in Nashville, and the article provides a hint that he likes country music.
She goes and visits him, but he says he doesn't speak "moms and SUVs." She returns the next day and impresses him with some knowledge of his music, despite being a mom with an SUV. He invites her in, and persuades her to drink.
The next day she doesn't remember what they did that night. He told her it had been magical. What kind of magical, she wondered. The right kind: he'd made a video of her singing with the new sound she'd been hoping he'd help her find.
They continue to work together but when she assigns him to work with Scarlett O'Connor he gives her prescription drugs to help with her exhaustion and to bring out her creativity. They have a short fling which Rayna puts an end to. He departs for Tokyo soon after.