Peladon was the son of King Kellian and the humanEllua, Princess of Europa. (NA: Legacy) When his father died, the boy king refused to take the throne, but the royal advisors Torbis and Hepesh convinced him to, and his mother allowed it.
Peladon wanted his planet to join the Federation, but Hepesh conspired against him, eventually taking the King hostage. Peladon was rescued by the Third Doctor and Jo Grant, whom he had fallen for, even proposing marriage to her, though she declined. (DW: The Curse of Peladon)