Adam (The Helliax Rift)

Adam was the hybrid son of the Helliax and Annabel Morden.

As he grew older, he struggled with Earth's atmosphere, with his skin blistering and his breathing becoming shorter. After taking him to the hospital, Morden locked him away beneath the Morden Clinic for his own safety. As he came of age, Adam sent out a telepathic message for his father to save him. The Helliax freed him and the Doctor took Adam and his parents to the Eye of Orion. (AUDIO: The Helliax Rift)

Behind the scenes
According to the script, Adam is "like its father - loftier, but scared, quick to lash out."