Volta's parents (The Runaway)
From Tardis Wiki, the free Doctor Who reference
Volta's parents were the Engarian mother and father of Volta, a teenager who ran off from his home planet and galaxy to explore the universe.
According to the Doctor, they were worried sick about his disappearance, and once he returned home they hugged him and left the TARDIS to return home. (GAME: The Runaway)