Hailing from Celestic Town, a small town near Eterna City in Sinnoh, Juno's journey to becoming a Pokemon trainer got off to a bad start. Isolated from most of the world and trapped under their abusive parents' control, they did their best to work with their piplup, Henry, and bond with him as a child. Growing up together in an unsafe environment made Henry and Juno fast friends despite piplups' infamous proud nature, and they soon became inseparable.

As a pre-teen, Juno's parents became increasingly paranoid and for Christmas Juno received a houndour, Greer, who was meant to be a watchdog to ensure Juno behaved when they weren't directly under their parents' gaze. Greer was immediately fiercely protective of Juno, and she quickly allied with Juno and Henry in the household, though kept up the guise of being a watchdog so as not to arouse suspicions.

To prove that they could be trusted with traveling independently from their parents, Juno completed all of Sinnoh's gym challenges (albeit a bit later than the usual trainer). They have no interest in becoming a Pokemon trainer in the usual sense, preferring to simply travel and learn about plants in each region.

After turning 20, they travel to Alola for a month-long family vacation. They find themself lost in the rain one evening after exploring too late into the evening on Ula'ula island, and stumble onto Team Skull's territory around Po Town. Guzma finds them, out on a walk late at night to clear his head, and he finds himself intrigued by the nervous trainer. He brings them back to Shady House for the night, saying that they should dry off and keep away from wild bewears. One night turns into two, turns into three, then five, then a week, until they have to return to their parents. After spending time with the ragtag Team Skull, they find that their family life feels more unbearable than ever and manage to convince their parents to allow them to travel independently a bit longer. Juno spends every available moment with Guzma for the remainder of the month, until the end of the vacation where they go back to their parents for a family dinner.

The dinner is disastrous. Juno panics and reaches out to Guzma, and without even needing to think about it, Guzma brings them back to Shady House where they're welcome to stay for as long as they'd like (forever, he hopes, but he doesn't say that).

A year in, and they finally confess their feelings for each other and begin dating, much to everyone's relief (mainly Plumeria's). After settling in more, the two of them decide to claim ownership of the Old Chateau in Sinnoh's Eterna Forest and fix it up to be livable. They travel between Sinnoh and Alola, often bringing eager Team Skull grunts with them, switching region every three months.