Harper: Harper shows no real affection for her Pokémon, despite their apparent love for her. She is shown as being snarky and defensive, though genuinely curious about her surroundings as she journeys. She is blunt and will state what is on her mind, as seen when she confronts Roark about his 'weak' speech. Harper has little control over her own actions and some of the things she says, as she is still a kid and has not yet learned there are some things you should not do or say... like kicking an old man in the shin. That's wrong. Her starter Pokémon is a Piplup given to her by her mom. The Piplup is female and named Merisoe, a name without meaning. Harper will name all her Pokémon, though their names have no real meanings.
Harper's Parents: Harper's Parents do have names, Caitlin and Tony. As mentioned in Across the Region the two met when they were young trainers and were rivals until they fell in love. Caitlin was the true battler of the family, she was an Ace Trainer in her day and often challenged the Elite 4 several times a day just for fun. Caitlin always won whenever Tony challenged her, which forced him to train harder until he was able to beat the Elite 4 himself. Caitlin and Tony both specialized in Water-Types. Not mentioned in the story is that both Caitlin and Tony loved music, and thus decided to name their kids musical names. However, neither of the two played any instruments or sang. They encouraged each of their children to learn an instrument and always told them "No matter how far you go, you'll always make music and we'll always hear it."
Cadence: Cadence, like both of his parents, specialized in Water-Types. His prize Pokémon was a Floatzel. Though in the story the Floatzel is not referred to by name, Cadence called his Floatzel "Rudiment". This indicates that Cadence was a percussionist. Cadence is also known for leaving eggs at the daycare for trainers in need and occasionally giving the eggs specific names. After traveling the Sinnoh region, Cadence moved to Almia and became a Ranger.
Melody: Melody specialized in Flying-Types, and her prize Pokémon was a Staraptor. Staraptor's nickname, not mentioned in the story, is Windfife. Melody is a singer, as shown in the Prologue: Ending the Perfect Day when she sings for Harper's birthday and Windfife accompanies her through whistling. Melody went to Hoenn after beating the Elite 4 of Sinnoh to learn more about Contests and become a top Coordinator.
Austin: Austin talks timidly and without confidence, though his actions are the opposite--as seen when he forcefully drags Harper back into Professor Rowan's lab. He's thirteen and originally from Johto, though he is currently traveling through Sinnoh on his second journey, his choice Pokémon being a Murkrow named Symphonic. Symphonic was an egg left at the daycare by Harper's older brother, Cadence, before he died. It is stated that Austin is colorblind and that his aunt runs the Pick a Peck of Colors Flower Shop in Floaroma Town. Austin is very studious and knows a lot of history, and it is hinted that he may be the type to be starstruck when meeting a celebrity (hinted at in Chapter 4: Jubilife, City to the Stars! when Harper exclaims about Barry being on TV).
Professor Rowan: This guy is nuts. Absolutely insane. To avoid spoiling anything later on, we'll just leave it at that!
Cyrus: Holy crud, this guy is bad. He's mean and nasty, to the point he purposefully attacks Harper after he shoves past her while heading towards Hearthome City. He makes eery threats about cutting Harper's soul from her body, and his Houndoom is portrayed as being just as mad as he.
Nurse Joy(s): They are ditzes, and they definitely can't handle Harper's attitude. Harper goes out of her way to say as little as she can to the Nurses, after her first encounter with one in Sandgem Town where she verbally attacked one and the PokéCenter was locked down.