Vaja is a supporting character in the story Skeleton Men of Jupiter.
Some time before the events of the story, Vaja was captured by the Morgors and taken to Sasoom (Jupiter). This turned out to be part of a plan Multis Par made with emperor Bandolian. Using Vaja as a hostage, the Morgors forced U-Dan to help them capture John Carter so they could interrogate him about Heliums military and defenses in preparation of their planned invasion of Barsoom. When learning about the situation, John Carter promised U-Dan to help him free Vaja. Together with the Savator Zan Dar and the Morgor Vorion, the two escape from their prison, steal a ship, and free both Vaja and Dejah Thoris (who at this point had also been brought to Sasoom). John Carter is captured again when he fights Multis Par, but Vaja, U-Dan, Zan Dar, Dejah Thoris, and Vorion manage to escape to Zan Dar's homeland Zanor.
Vaja is not seen again in the rest of the story. At the end of the story John Carter arrives in Zanor and expects to be reunited with Dejah Thoris, but it is not revealed if she and the others are actually there.