When they first appear, Eon has them fight Heatblast. After a short fight, Heatblast defeated them.
Later, they were seen with Eon hidden in the Clock Tower. In there, Eon suffers a headache. One of his servants tries to help, but he prevents this and attacks him, cruelly ordering the others to "let him die".
Eon uses them only to gain the advantage in battle and to do some of his dirty work.
They are believed to be previously enslaved humans or creatures belonging to Eon's planet, a race of the same species, limbs of the same species and under-age mutants or beings from another dimension.
They appear for the last time when Ben (as Eon), calls for them and they took the plumber's weapons away. They were then destroyed when Ben regained control over his form.
In Ben 10,000 Returns, Eon used his servants to attack Ben 10,000, but they were all defeated. They later appeared in the present, fighting alongside their master. After Gwen used a spell to freeze them, it was revealed that they were alternate versions of Ben himself, who had their powers drained and placed under Eon's control. When Eon vanished from this universe with the destruction of the Hands of Armageddon, everything he did was undone and the alternate Bens were returned to their respective timelines.
In Ben Again, Eon summons his servants to aid him in the final battle. They resemble their Ultimate Alien selves, but since the alternate Bens were restored to their own time and place after Eon's previous defeat, now they are just robots.
In Ben 10: Race Against Time, they are completely black, except their faces, wearing a brown tunic and a helmet with mirror effects. Their faces resemble a pig-nosed ogre, with wrinkled skin and their eyes closed.