Sustenance is a mysterious green liquid that Cybersix must regularly consume in order to survive or risk withdrawal symptoms and possible death in the Cybersix series. It was originally created and currently produced by the mad scientist, Doctor Von Reichter, who uses it to sustain his experiments.
Cybersix acts as a vampire in the comic series, sucking the sustenance from the necks of Von Reichter's creations, although she has no fangs and simply makes a wound with her teeth. Her withdrawal symptoms include weakness, headaches, sweating and drowsiness. Initially as a child, she drank sustenance from glass jars that her slave father stockpiled in a briefcase that lasted into her adulthood, and when it ran out, forced her to attack Technos that resided in Meridiana that acted as normal civilians. From these, she had a stable supply of sustenance.
The irony does not escape Cybersix or Von Reichter, who are aware of their peculiar situation. Cybersix wants to be free from Von Reichter but must rely on him to continue producing sustenance so she can live. And Von Reichter wants to end Cybersix and could cut off her supply of sustenance but it's a crucial element in his creations and plan for world domination.
Von Reichter had sought to rectify this problem by poisoning the sustenance supply in his creations, a change that Cybersix was unaware of until she consumed it and found herself delirious and suicidal. Maura Click and Dostoievski managed to take care of her and even bring in an unaltered sustenance from a proud José, who had refused to have his changed. The sustenance afterwards was reverted to its original self.
Data 7 also drinks sustenance and is made of it. In one instance, he allowed Cybersix to drink it to survive after failing to catch any of Reichter's creations. Cybersix's clone also requires sustenance but to escape being killed, she stowed away as a worker on a ship and her fate is left unknown as she is now without a stable supply of sustenance away from Meridiana.
It's not known if sustenance appears in the live-action series.
In the animated series, Cybersix obtains sustenance from Fixed Ideas after they die or "deactivate", after which their body disintegrates and leaves behind a single vial of sustenance. Withdrawal from it results in her left arm experiencing an intense pain.
- The French and Spanish comic editions refers to them as "Substance".
- Though an important plot device in the comics, the animated series only brings up Sustenance in two episodes, the first episode and the last episode.
- In an interview with Carlos Meglia, Meglia reveals the censorship concerning the sustenance in the animated series arose out of the wish to appeal to American audiences.