Prince Astor and Princess Verbina are royal Lebidopterins which first made their first appearance in Episode XLVII: Jack and the Flying Prince and Princess.
They are the royal sibling heirs to the throne of a humanoid moth like race called the Lebidopterins. Their home planet is Chrystallis. The Lebidopterins' archenemies, the Squoomians, return after a decade to lay siege on their capital. The royal family sends their two children, Astor and Verbina, to bring the Royal Navy back with their robot servant Chitron 6 but when their ship is damaged after a Squoomian attack they have to set down on Earth.
After they crash land on Earth they soon find out that Earth's gravity is stronger than Chrystalis and thus they cannot fly. Aku's robots come and take them before Aku, who is less than sympathetic – he imprisons them. He also destroys Chitron when he tries to stop him. Jack rescues them and takes them back to their ship so they can repair it. Aku's Beetle-drone forces close in as they conduct repairs. Jack has to hold the drones off as they finish repairs but they refuse to leave him and generate an anti-gravitational force field, giving them the advantage.
Together the three of them defeat the drones and the prince and princess thank him; even though they are strangers he risked his life to save them. Jack explains it's because their stories are very much alike. Astor and Verbina go to summon aid for their people. Chrystallis is saved and the Lebidopterins erect a statue of Jack in his honor.
After the past Aku's destruction, the war presumably still take place. It is possible that their experience on the altered future Earth will turned out differently. Since Jack's rescue of them never happened given that there were no Aku to hold them captive, their memory of him was erased.