(sorry, I couldn't think of anything, so do whatever!)

Appearance
Alien Form: Blue skin, shoulder-length wavy blonde hair with a full fringe, and blue-gray eyes. The band wears coordinated orange and white outfits with headbands, wristbands, and belts adorned with red jewels.
Human Form: After being captured and transformed by Earl de Darkwood, Arpegius has fair skin, brown hair, and light blue eyes. He wears a red t-shirt with a white stripe, black leather pants, sneakers, and mind-control sunglasses.
Child Form: Retains light blue eyes with simplified band attire.
Personality
Confident in his musical abilities and takes the lead as the guitarist.
Brave, determined, and strong-willed, often facing danger to protect friends and fight injustice.
Loyal to Shep and the band, showing initiative in critical moments.
Possible Bond with Stella: Fans have speculated about close feelings between Arpegius and Stella, suggesting a nuanced relationship.
Role in the Story
Initially performs with The Crescendolls on their home planet.
Captured and transformed into a human by Earl de Darkwood along with most of the band.
Briefly escapes but is subdued; later freed by Shep.
Participates in rescues, battles Earl's humanoid troops, and confronts Earl himself.
Climactic Action: Throws the final golden disc into a lava chasm, leading to Earl’s apparent death and Darkwood Manor’s collapse.
Aftermath: Restores the band members’ alien forms, honors Shep through a memorial, and participates in a final concert before returning to their home planet.