It's Not You, It's My Enemies: This turns out to be one of the real reasons he left Reona. He was heading off to rejoin and work as The Mole against Gunner's genocidal scheme and didn't want her drawn into the danger.
Matchmaker Crush: Efrem had intended Reona for Zap all along, but ended up in a relationship with her for a time.
The Mole: He was seemingly this to the Resistance. Though he is actually this to Gunner. Gunner is well aware of this however, and has threatened to kill his "friend" if he actively goes against his plan.
Revenge Before Reason: Most of his race was destroyed by the GEF, and he seeks to Kill All Humans as revenge. He is willing to do anything to accomplish his vengeance, even torture or murder his best friends. Vitale knows that Gunner is beyond dissuasion, but points out just how pointless his actions are.
The Unfettered: He is willing to kill anyone who gets in the way of his quest for revenge. Even his closest friends, the only other survivors of the destruction of his world.
Puppet King: While nominally in charge of the GEF, Maximus and Feonix are able to play him like a puppet by baiting him with promises of money. However, they apparently do get tired of technically answering to him and assassinate him. It turns out that they originally had been perfectly satisfied using him as a figurehead, but Gunner planted a desire in their minds to get revenge and seize direct power.
Shoo Out the Clowns: While thoroughly evil and even genocidal, he is quite comical. Naturally, he gets assassinated by his own generals as the comic starts taking a darker tone.
A GEF commander and the head of the Psychic Academy. His character is gaining importance in the story.
The Starscream: He was originally satisfied with using Billings as a Puppet King, but after Gunner plants a desire to rule directly, he works together with Feonix to murder the President in a coup to seize power for themselves
The Starscream: He supposedly betrayed his people, but in actuality did this to seize power inside the GEF on his people's behalf. For a long time, he was satisfied with using Billings as a Puppet King, but Gunner used his psychic powers to plant a desire for vengeance, resulting in him working together with Maximus to assassinate Billings and seize power for himself.