They are introduced in "The Secret Library" as illustrations. They once lived in the Royal Stables of a far off land. When Mazzimo left home to find Wildwing Valley, they were very sad to see him go and couldn't understand why he left due to having a kind master and liked living in the stable.
They officially debut in "Best in Air Show". According to Minimus, after Mazzimo left, they practiced Stunt Flying as a hobby. They were so good that their stable master Count Barnstorm started the Flying Starwings with them as the stars. However, Mazzimo left the family, and Minimus was a late bloomer as a foal, making both of their children unable to join the show. They first appeared after Sofia and Minimus flies up to them. Gemina is happy to see her son again and meet Sofia but she and Argus are not happy about how high and fast he was flying. This is because when Minimus was a foal his first attempt at Stunt Flying made him crash. Sofia and Mazzimo, who came to see their show, tell Gemina Minimus is a better flier than he was back then but she doesn't listen. It takes Minimus to save Grand Mum to make her see that they are right.
Argus is the typical hen-pecked husband and Gemina is the typical overprotective parent.
Mazzimo resembles Gemina more, while Minimus looks more like Argus.