Fourth Drax

A renegade Time Lord with a knack for tinkering, Drax had known the Doctor before either left their home planet of Gallifrey.

Youth
Drax attended school on their home planet Gallifrey with the Doctor. (DW: The Armageddon Factor) Both belonged to the social group known as the Deca. (PDA: Divided Loyalties)


 * At some stage, Drax decided to strike off from Gallifrey and travel the universe.

As a Renegade
Drax did jail time in Brixton on Earth, where some of the local accent rubbed off. When the Doctor's search for the sixth and final segment of the Key to Time, the Doctor and Romana arrived on the planet Atrios, which was at war with their neighbouring planet Zeos. In reality, the planet Zeos was deserted save for a giant computer called Mentalis, which was controlling the war. The true enemy was a third planet called the Planet of Evil, ruled by The Shadow.

The Shadow had imprisoned Drax and made him work for him. He agreed to help the Doctor. With his assistance, The Doctor recovered the final segment of the Key to Time. Afterwards, Drax stayed on Atrios to offer his services to help rebuild. (DW: The Armageddon Factor)

As with other Time Lords, his ultimate fate in light of the Last Great Time War remains a mystery.

Behind the scenes

 * The exchange between the Doctor and Drax regarding his accent in The Armageddon Factor would be echoed decades later in a similar exchange between Rose Tyler and the Ninth Doctor in Rose.


 * The Make Your Own Adventure with Doctor Who book Search for the Doctor included Drax as a character that the reader/main character could interact with. He and K-9 helped you defeat Omega and rescue The Sixth Doctor.  In this book his TARDIS was in the shape of a convertible car, the number plate of which read "TARDIS."